Open FBI, go to Titles -> (the game you want the save from) -> Browse Save Data -> <current directory> -> Copy all contents. Press B until you get back to the main menu. SD -> <current directory> -> Paste. If you want to keep things more organized, just do "New Folder -> (give it a name and open it) -> <current directory> -> Paste" instead of pasting in on the root of your SD card. You can also get saves from NDS or DSi games with FBI, but instead of selecting "Browse Save Data", you have to select "Extract Save Data", and it will automatically make a folder called "fbi" on the root of your SD card with the saves inside. Don't want to do all of that? Just install JKSM. That's why people use JK's save manager anyway.