Don't worry about the link, we're still fixing that.
Go to your User CP, located on the fight side of the forum, then scroll down and on the left side it says "paid subscriptions", you should be able to purchase a membership from that page.
If you can't for some reason, I'll have an admin get you all set up no problem.
I suggest buying the lifetime membership by the way, there's a few little additions (like the name of people who leave you rep).
“Anna, my strong, terrifying Anna.” -Cas
"You lack the requisite spine and testicular fortitude to study under me" -Elodin