registering for capstone?

[Argo]

I registered for the capstone and it said click ok to pay for the course. It took me to a page that didn't allow me to pay and it just had a return button. I don't remember what the page said, I wish I would've paid closer attention. Now the course is just sitting there, registered but not paid for. If I don't pay for it quickly they'll probably drop the course. How do I pay for it?