Sure! Below are the steps for creating a SEGMENT to find those members of your account that aren't in any audience group. Will you please let me know at which step you're hitting a roadblock?
On the main audience screen, click on the SEGMENTS tab next to Groups.
Click the Create a new Segment button.
Choose Audience groups from the dropdown menu and click Add.
Search for people who are in LIMBO (not in any group) and click Add.
Name and save the search.
Once you find the people in limbo, you can rescue them using the gray toolbar at the top: choose select all members and copy them to other groups. Select the group(s) where they should be added, and Emma will move them out of limbo and into their new group(s).