to learn how to pick up stitches, go here
. You'll have to scroll down to "assorted topics."
as for working on a circular needle, it really sounds more complicated than it really is. so long as your circular needle is short enough (your pattern should tell you how long it needs to be - shorter is better than longer), you shouldn't have any problems. you'll pick up the stitches, and then when you get done, you should be back to where you started. move the stitches you already first picked up to the end of the needle in your left hand, the stitches you most recently picked up shoud be on the needle in your right hand. just start knitting around. on that same page with the video about picking up stitches, there's also one for knitting in the round on a circular needle.