There are a number of different ways to make changes to your paper now that you have a rough draft. You may find that you need to do some more research to support or dispute claims, edit the sentences of your paper, revise the structure of your paper, or proof read to eliminate errors.
This video from the Purdue University's Online Writing Lab (OWL) is really helpful in wrapping your head around the revision process. You can find more here on the OWL's website to delve deeper into revising and editing tips and tricks.