To donate you can go
here. That's from the User CP at the bottom where Paid Subscriptions are.
The userpage subscription is the first subscription you'll see and is only 42 cents a month, or five dollars a year.(I think) In my opinion, it's worth it. I enjoy having a userpage on TTC and I plan on getting one here before the end of next year.(Only problem is I'd like to have photoshop to make some nice images before i buy one.)