You're in high school... but how old? If you're under 16, there are different rules for how you can work.
My suggestion: Take an afternoon, go to the local mall, and ask every store for an application to fill out. *DON'T* ask if they're accepting applications -- ask for one instead. Sales trick there... don't give them an opportunity to say No.
I did that in what I call my "summer of ten jobs". I hit one wing of the mall near my house... perhaps 30 stores. Got one job that day, and another that night.
A suggestion... dress nicely when you go. I'm not saying coat and tie, but something that looks nicer than jeans and a t-shirt. That first impression counts... a lot.
If they say no, ask if they could point you to another place where you might find employment. They may not offer anything, but then again, they might...
Good luck!