For the MP-610 you can make playlists using Coby Media Manager.
In Coby Media Manager there's a help section that gives next information how to make playlists:
You can create playlists to group songs (example “My favorite songs”).
To create a playlist, right click in the Playlists section (located on the left side of your Coby Media Manager window), and choose Add. A playlist is created. You can rename it using the F2 keyboard key.
For Coby Media Manager download, go to next site:
Install the software as told and when running the Manager for the first
time go to the page top: Tools > Device Manager..
Select your player from the Devices List, this software can be used for.
Add the device, AC or AL version. Finally enter OK under the Favorite Devices list.
All support for the MP610:
If this was helpful, I'd appreciate your answer.
When needing more help, just add a comment in this thread.