I am really into photography and will probably want to major in it. Colleges use high school grades as an indication of how well you will do academically in college. Our first piece of advice is to put more emphasis on your grades. You don't need a 4.0. Just make sure that you are trying your best to do well in class.
Colleges also look carefully at extracurricular activities like photography.
First, consider taking some photography classes at a community college or adult education center. Next, think about getting some of your photos published. Start a photography club or journal at school. Surely there are other students who enjoy photography. You could do it online for free.