Lisa asked me to show examples of how we edit a submission. You can do it several ways. If it's a face-to-face group, write on the paper itself. When you hand it back, it's easy for the writer to see what you've edited.
If it's online, I use different methods. I suggest the use of Comment boxes. (Two of the publishing houses I work with use only Comment boxes for their edits, so it's good to learn how to use them.)