well you put the disk in select computer and double click the disk drive D: you can get steam games with virtual disks so you will never need one if you purchase the games from their steam online store.
In the games tab, click "Activate a product on Steam..." to install the game if you have the CD. If you bought the game from Steam, you should see it on your games list. Right click it and install it.
Tunngle for LAN or Phoenix (to install and play single player steam games) still looking into tournament MP.
click x on the game and click install
Well... Your question is not clear to me. If you bought retail games, you don't need it, but if you want you can download steam app and register your game on steam app. I bought COD 4 retail which means that I bought CD at gameshop in downtown. After installed my game without steam app. but I registered my COD 4 on steam app so I can install my COD 4 without CD.
All of the games that you have paid for with your account will still be on your steam name even if you delete steam or reinstall your computer. Install the steam again and log in with username/email + password and all your games will be in your library again you just have to redownload them all over again.
Do you mean install the game so you dont need a disc anymore? Or install a segment like on MGS4.
If you install windows, then yes
This is possible, but only if the game already is available to buy from the Steam store. For example, if you have Half Life 1 from back when it was not on Steam, you can validate the CD key on Steam...and then play it without the disc through that. Games that Steam doesn't support however can not be translated over to Steam. Quite a few games are on Steam though, including EA recently adding a number of their games to it.
...thats more of a computer question
--- Update --- This is not possible; you must use a macbook install disc or a generic install disc.
put the disc in into the disc drive, and follow the steps, it will install, you dont need a manual to install a game
If you want the game download a program called Steam. With Steam you can buy games and other stuff. Steam is also legal to use because you just buy games. Anyways with steam click on STORE then search Dungeon Defenders. Buy it, then install it and your ready to go from there