Hi Brenda!
When you click on the "Make a Payment," and then you see Tinker Bell with the "processing payment" message, let that message stay there without touching anything (if there's a lot of website traffic, it can take up to 5 minutes some days to process your payment).
After then, it may take you back to your My Disney Vacation page and sometimes you don't get the payment confirmation on the web page (although, sometimes later, it'll come up as an email message in your Inbox). It hasn't been an exact science, but the payment eventually does go through...
If, however, you've tried this more than once with no success, I'd contact Disney's Technical Support Desk just to make sure there's nothing going on with the site, or even one of your machine settings, that may be causing the issue. The Support Desk is 407-939-7765.
Good Luck!