To clarify...
Synchro monsters are summoned via a smecial summon called "Syncro summoning" (that much makes sense).
You need to have ANY monster + any Tuner (a new type of monster) that equals the EXACT level of the synchro in question. Some synchros need certain types of monsters, too, like AQUA or Winged Beast, etc.
example: Stardust Dragon (8 stars, 1 Tuner + 1 or more non-Tuner monsters)
you can have a six star... like say, Jinzo (remember that asshole?) and any two star Tuner (I'll throw in
Kagemusha of the Six Samurai as an example. You remove the two from the field at any time to "Synchro" for 8, and bring out Stardust Dragon.
The new Xyz monsters are MUCH more simple. They have a "Rank". You need to monsters with the same Levels as the rank you are trying to summon. So if you want to summon a 4 star Xyz you take two monsters you have at level 4 and you "Xyz summon" them; stacking the Xyz monster ontop of the other two. Xyz then have effect involving discarding said monster cards, like, "discard one Xyz material monster to negate an attack".
@ both of you: You're probably using "Future Fusion", to discard 5 dragons from your deck in order to bring out Five God Dragon two turns later; whilst protecting FF and FGD. My friend uses Red Eyes Darkness Metal, Prime Material Dragon, and Future Fusion in his dragon deck. MAN is his deck tough (it can easily take out the likes of "Top Tier" decks like Six Sams, Dragunity, Gravekeeper's, etc).