TournamentService has a context sensitive help system - meaning, you can press the F1 key in any window at any time to get help with whatever you are doing.
You can also highlight an item in the menus and press F1 for information on it's function.
Or, search this help file by using the tool bar above.
To get you started, here's a handful of starting points to navigate from:
How to use TournamentService - An overview
The main window
Integration with local or FIDE ratinglists
Rating data exchange