When my editor began sending me his edits, he said something that is great advice for all first time authors. “Don’t be put off by all the “red ink.” When you wrote this, you were focusing on what to write. My job is to focus on how you’ve written it.”
The best tool to use for editing is MS Word. Send your editor a copy of your latest manuscript. When you get it back, I recommend either making the changes to your original or changing the one you get back. You should retain the editor’s copy in your email program.
Your editor should use the Review tab to add comments and make changes (enable the Track Changes button). If you decide to use the same copy, you can Accept or Reject those changes (Review tab) and delete the comments.