I worked at DGS a while back. Delta non-rev is pretty complicated and very unpredictable.
There are two facebook groups that can help.
One is for Delta Non-Rev. There are plenty of people that can answer your questions there.
The other group is for all the non-rev loads. Essentially ZED. All airline employees checking loads for each-other to find out if you are going to make a flight or not. Whenever I asked for a load I would also check a load for someone else. It keeps the group going.
Turn off the notifications for both groups as you will get bombarded with notifications
Do not post screenshots of travelnet- that can lead to disciplinary action very quickly
No one ever gave us a non-rev class, but you can learn everything in the groups.