Hi man, you go on http://www.intertopspintour.net -> you click on Tennis Elbow.
Afterwards you click on either "Register" if you have not signed up yet or "Tournaments" once registered, to have access to the tournaments list which is frequently updated with new tournaments.
After you just click on sign-up, and pick your character.
You have 2 or 3 tournaments every week, you can choose to play a challenger/Future and an ATP250 at the same time if they don't start at the same date I think.
If you're a beginner I advise you to play every single challengers/future it's a good way to start on the tour.