Carry on answering Minox's questions but I reckon a quick overview of things you are likely to be facing is in order.
Your computer by itself barely knows how to boot but it will deliver it to a certain point where the Master Boot Record (usually seen as MBR) takes over. Here in the case of windows the windows boot methods (which changed a tad for vista but more on that later) take over and in the case of linux there is grub(2), lilo or something similar. Macs are subtly different here and kind of similar to the UEFI bootloader things you might have heard some bitching about in the run up to windows 8 but the linux crowd saw it coming and have workarounds.
Windows traditionally rode roughshod over everything hence the usual suggestion for those new to the whole setting up boot menus thing that they install windows and then install linux/bsd/whatever which are used to handling such situations.
On partitions
Classically there are two types
1) Logical partitions
2) Extended partitions.
Traditionally you are only allowed four of the former per drive (a limitation as the whole PC thing is very old) and most older operating systems technically including XP will only boot off such a partition. Windows tends to be installed over a single partition although the move to SSD and people being sensible and sticking my documents and such like on other drives (which windows vista and beyond almost encourage and it was not hard for XP either) has kind of changed that. On a standard windows system the only other partitions are usually backup partitions if your vendor is too cheap to ship a driver/windows CD and gets you to burn it (although better vendors do have some decent restore and alternative/just get me on the internet type options). That said before virtual machines came along I was known to split/copy windows across several partitions in the cases of programs that did not play well together (usually highly expensive field specific software) and allow them to be boot between each other but I do not want to return to those memories right now (see boot.ini if you really care about that sort of thing).
Extended partitions have a few quirks but realistically you are allowed some 15 or so (best if you start them as the final partition in my experience) although it will probably become impractical long before then. Linux is usually quite happy being spread across these when done correctly.
There are all sorts of little flags you can set on partitions although the most useful to know are boot and hidden.
Boot does what it says and is the partition that the computer will try to boot from (usually given to grub/lilo unless you have something exotic with easyBCD) and hidden is something that most vendors mark their recovery partitions (and which windows tools have a habit of politely ignoring when you want to try getting rid of one).
It gets a lot more boring than that but if you have that on lock then you will know as much as you need unless you actually want to start programming tools to handle the things in the first place.
How to make partitions....
Windows features two main methods for my money
fdisk - the old method that has been around since before windows 95. Kind of sidelined unless you are on a setup CD or in some version of dos.
diskmgmt.msc (either find it in the system32 or equivalent directory or use the run command/vista or 7 typed thing - the method most will use in windows even if they do not realise it and just use the basic format options.
They are nice enough but not a patch on a proper tool and prone to being a bit limited by actually being in windows at the time (see pulling yourself up by your own shoelaces).
Proper tools
EASEUS Partition Manager was already mentioned and it is good although technically not free and if it is superior it is not superior enough for me to take note over the tools in the next sentence.
Gparted which gets bundled into parted magic
http://partedmagic.com/doku.php as well a standalone gparted livecd and many other things like those I will mention at the end, it is my chosen tool unless I have to do something very special for a custom server or something at that level.
It can format partitions (to just about every filesystem in popular usage and a few others besides unlike windows which basically does FAT, FAT32 and NTFS), it can make new partitions, it can copy them, it has a fairly decent set of checking and drive recovery abilities (though it is not the be all and end all there) and my favourite option is the one to resize and move partitions including NTFS ones. It can take several hours if you are dealing with a large drive full of data but it is an invaluable ability for when your drives are partitioned as a single partition across the entire drive.
Linux itself can be done on one partition but many opt for three (or four if you count grub)
1) Grub or lilo- you give a couple of hundred megs and it sticks the boot loader (itself a fairly cut down version of linux) so as to be able to boot.
2) The root partition - this installs linux and probably your programs (although they can go on a further partition)
3) The user/home partition - here you have your documents, files and maybe some settings depending upon how you configure programs or they configure themselves.
4) The swap space- windows tends to call the idea virtual memory or a paging file. The idea is you have a piece of hard drive to use so as not to run out of RAM for active programs.
Linux handles all this almost transparently (there are no drive letters in linux which is quite nice in some ways as drive letters are a somewhat archaic and limiting concept). Most good linux installers (definitely including that of linux mint) may well half prefer it if you just give them some unpartitioned space to work with though you will be given the option to change sizes and mappings (see also fstab) before pressing install if you want and there is nothing stopping you from going manual.
The nice thing about having a home partition is you can upgrade your linux install fairly painlessly or even have several use the same one or even do something really exotic like stick it on a network share. For the record as well linux type filesystems can be read in windows with tools like
http://www.ext2fsd.com/
Theoretically you could then uninstall linux by deleting the partitions, maybe growing the windows one back and then making sure the boot flag is set to the main windows partition. I usually leave grub installed and configure it to be nearly silent (autoboot windows after a single second) but play it how you will.
As mentioned windows does not play well with others unless you bash it really hard, to save that though there is either grub/lilo or kind of related but from the windows front is easyBCD.
EasyBCD is not strictly like grub/lilo but many will forgive you the distinction for as far as pretty much everybody is concerned it allows you to choose what you boot into. The distinction is mainly that EasyBCD is very heavy on the chainloading idea and as such you theoretically could probably go through about 4 steps to choose what you ultimately boot into via software alone.
Personally I can work with either EasyBCD or grub/lilo as grub/lilo can boot windows quite happily and without any real issue.
Final note- grab yourself a copy of Hiren's boot CD (no links I am afraid but it should not be hard to find) and Ultimate Boot CD aka UBCD
http://www.ultimatebootcd.com/
Both have fairly extensive boot options so even if you hose up the hard drive boot setup they will at least be able to catapult you into an OS from which you can do something and they both also contain highly specialised boot tools to fix hard drives, reinstall boot managers and perform other such niceties. It does occasionally happen that the boot for a machine gets corrupted by something and when you inevitably get called in with the cry of "fixit fixit fixit" you may well be able to get the thing up and running in less time than it took you to fish the disc (or bootable USB if you are fancy) out, bonus is parted magic will also include testdisk/photorec which can fix the slightly less common corrupted partition table issue or recover files from it.
Anyway enough waffle. Hope you get it sorted so you can try some stuff out, I know I have just tapped out a mini essay and I assure you most of this was learned as it came up rather than crammed in a single sitting, not to mention linux really can do it for you and might even be able to shrink your windows partition just by your saying "make it happen" (I tend to do things manually mainly because I can or because I am starting from scratch so I miss out on some of the automated niceties that crop up).