I am brand new to community and organized play, I am looking for some events in my area/ (Tampa, FL.)

How do FFG championships work are there regional's etc etc? Or can you just sign up to be there?

How it works depends on the store. If you are in Tampa check out Armada games. In St. Pete check out Critical Hit Games. Crit Hit has a Tuesday night casual meet up (I don't know what Armada has that way). Both stores will have Store Champs soon.