how can I get a job at age 15 teen
Go to a place that hires at 15 (make sure, because not many places do) and ask for an appliation.
You will probably have to get a worker's permit.
Ask your guidance counselor at school if you'll need one.
If you do, you get it from the school.
But keep in mind that most places are looking to hire adults.
So many adults are out of work, so they are the top priority.
Check out this site: www.happy-wahm.blogspot.com
Adults are working part time with that. But they also accept teens 13 and up.
You go to a business and ask for an application.