Steam activation?

Hello chaps, I've bought a (boxed) copy of the game and have installed it and everything, but don't seem to have access to the editor in Steam. I've had a look around this forum and everyone seems to suggest that I need to activate the game to get access to it - but this has never been an option, I haven't been prompted to do so. So my questions are 1) how do I activate the game?, and 2) how am I able to play the game when I haven't activated it?! I've installed it on two different computers and not been asked to activate either time!

Cheers

Si

I'm assuming you know to look in the tools section of Library on Steam to find the editor?

Exactly what I was going to say...?

Yeah I did, it's not there! I'm sure I'm just doing something brainless and thick, but can't work out what.

Found the activation bit finally and now it's there, apologies for self-indulgent thicko thread.