Submitting a form through button press

I have an http request that opens up a form. It uses a POST request and fills in most of the fields on the form, but I don't know how to get the form to submit within the test run. The form and what comes after(what I want to get to) are at the same URL, so I can't bypass the form page, I don't think. Is there anyway to simulate a button press, or somehow tell the request to submit the form after filling out that page?

Thanks.