Configure new ID column in wpDatatables Wordpress

The table we are working on is visible at [login to view URL] This new ID column intended to auto populate as the record for that user starting with record one for each new user. It should consist of the UserID# and an auto-incrementing number. If the user is #35 for instance, values for records 1-5 might be 35-1, 35-2, 35-3, 35-4, 35-5. Assistance is greatly appreciated. My skype id is tedpenner. The help I need would be via Teamviewer.