How to get a booking for a solo artist?

I am a 13 year old singer. Whenever I look up castings for singers it's always for a band or something. But, I am more into the solo artist thing. Like Nicki Minaj, Selena Gomez (thin list could go on forever) is what I'm interested in... Being a singer with nobody else (well, except the musicians lol) So, how (where) can I find castings for things like that? PLEASE HELP!!! Thank you :) xoxoxoxoxo