The instructions and link 3 in my thread will get you what you want. Break it down, step by step, read and reread, ask questions, understand what it is you're doing at each step, then do it and if still stuck ask some more questions and you will arrive at your goal.
We all start as Dunderheads, don't worry about that, just make sure you're comfortable doing things before you do them.
A description of what takes place in each of the 6 steps I provided:
1....link with how to do stuff
2....install software on your pc that lets you install software on your phone
3....install sprecovery, which replaces your current recovery app with a rooted version that lets you overwrite system files the stock recovery app can't.
4....make a backup in case the future doesn't go as planned
5....install the rooted version of ese81. ESE81 is the release version of android 2.1 on your phone right now
6....install wifi tether and you are done.
edit: doh..did I just call the op a dunderhead?