Ii'd like to know how to approach someone to find a job

The first thing is to be honest. Don't tell them you're 13 if you're really 12.

Fact is, even if you're 13 your choices are limited. Most places have rules about hiring. Where I work you have to be 16. I only know of one place that hires kids that are younger, and that's McDonalds.

Go to McDonalds, ask for an application, bring a resume, and apply. If they're interested you'll be called for an interview. But be honest, not like what you did here.