Sorry just saw this. You should have PMed me on U-E.
JRut and Aggie gave you a pretty good breakdown. I'm almost positive that Willis falls under the Houston Chapter, our boundaries stretch pretty far north. You'll want to get your start calling for TASO because scholastic games get you experience points, Peewees do not. The better paying peewee leagues are also harder to break into whereas subvarsity games are plentiful.
Your first year in Houston you'll call anything below varsity. Jr high plays M-Th including private schools. Freshman and JV usually play Wednesday and Thursday. There's also six man football you can get involved with. That's the quickest way to start calling varsity football.
Training classes will be starting soon so don't delay in contacting chapters. Based on where you live I'd contact both the Houston and College Station chapters. Good luck and feel free to PM me if you have any questions.