There is a difference between revising your paper and editing your paper, but it's not always an easy distinction for students to understand.
You should proofread your paper to edit mistakes such as spelling errors, punctuation mistakes, common word mix-ups, and other mechanical problems. While the editing process targets grammar problems, the revision process should focus on readability, logic, and clarity.
When you revise a paper, the first step is to read the paper to see if it flows from one topic to another in a sensible manner. You examine the paper to determine if the organization is logical, if the paper fits the actual assignment, or if you veered off-topic at any point. During the revision process, you will find yourself rewriting paragraphs to make them sound better and to make sure they support the claims you made in the thesis statement.