Beginner Sock Help!

Well, I've joined the Sockapalooza and I've got the details of my sockapaloozee. I've been looking at some sock patterns and I want to do something pretty easy, especially as I'm a beginner sockapaloozer.

I saw Joan's Socks which seem to be fit the bill, and they are worked in double-strand worsted weight yarn. The pattern mentions length, and I have my 'paloozee's foot length, so I can figure that bit, but I also have a circumference, and I have no idea what to do with it!

I've been reading Socks 101 and the concept seems fairly simple.

Something I've been considering is getting an anonymous-ish email from Yahoo or Hotmail, so I can email my 'paloozee and we can get to know each other and talk (being careful, of course, to keep my identity secret). Maybe other 'paloozers could do the same. I'd hate to be the only one, and have that in and of itself identify me!

It seems all I have to decide is what natural fibre yarn to get, without breaking the bank, and what the heck to do with that circumference measurement. Ideas and suggestions welcome!