Forum:I bought the game installed steam what next ?

Hi folks,

I am new to Steam and Left 4 Dead. I installed steam (not the game on the retail cd?) and now I am flabbergasted what to do next ... Ok ok I have plenty of experience with Gamespy, EA servers and Ubi.com but Steam no sir. Is the some place where I download the game after having entered my cd key ?

Kind regards

Me