Umm Crysis 2 is the first game that i ever pre-ordered and i pre-ordered it on steam, after woulds it gave me a recipe with a confirmation code, do you know what do i do with it and how to do i link my steam pre-order into my gamesas account to know that i pre-ordered the game

Just wait for the release. If you preordered something with steam the entry in your gamelist will become white on release. Then you have a button "Install" wich downloads the game(In Steam you dont need to install it). I think the accounts will get linked after your first login.

Relax Steam is easy. The code they give you if you run into any trouble and yes some games do require you to enter it. It pops up on your screen in a little window. Most Steam codes and games are automatic and a little secret. If it is a big release, as I feel this is. You will probably just have to go into it. The MP part of course I am not sure, but I think you just enter your account info for your EA Account.