I just got a network adapter and HD for my ps2 also. At first, the tutorials were a little confusing, but it all worked out in the end. Now I've got 20+ games on my HD, and it rocks!
Basically, you've got to get some files onto a memory card. There are a couple ways to do it, I used an action replay max with a usb mem stick. Once you've got the files on a mem stick, you've got to use a ps1 game as a "trigger" disk to make the ps2 boot off of the mem card.
I've got HDLoader on my mem card along with an ftp server and a few other tools.
-PMF