Once you've activated Ad Revenue, your account will automatically collect your ad revenue. Two things that are important to mention though because a lot of people are unaware going into it:
It might take a few days for any ad revenue to actually appear. If money doesn't show up right away, give it a few days.
You're not going to be seeing tons of money right away. The CPM is kind of dreadfully low atm so it's gonna take several thousand views to pull in even a dollar. So you might also not be seeing anything right away because your views haven't amounted to a number that can be properly expressed yet. I don't know what your viewcount is like though
You can withdraw your Ad Revenue starting at $25. This means that if you've only got $5, you have to wait until you hit $25 until you can withdraw it. This is mainly to reduce transfer fees and the like for both Tapas and yourself.