You could have asked that in your first post as well; this iteration of back and forth is likely to be followed with you asking what they do.
For most trainers, the idea is to open the trainer, then run the game.
If it's a trainer that just does things automatically, just keep playing the game.
If it's a trainer that requires you select options and such:
Switch focus to the trainer (Alt+Tab), select options, go back to the game where the changes are made.
Read (technical);
Read (simple);
Google (mandatory).
