Typically, you will want to create a Code Review after you have created a Story/Task in Rhythm and you have associated that Story/Task with a specific file or change set during your SCM commit. How to associate your commit with the Story depends on your SCM tool. To associate a Story/Task with files during a commit, depending on your SCM tool, see StarTeam or Git. If you already performed a commit and didn't associate it with a Story during the commit, see Add Existing Commit to a Code Review.
To create a Code Review:
If you have already associated a commit with the Story, the files in the commit will appear in the View by list.