What courses can I take in college/high school to become a graphic designer?

I'd suggest trying out a few different types of digital design, because there are lots of different potential careers that could be a good fit for you to combine a love of art and technology. A graphic design class could give you experience with learning text & graphic layout. I took an animation class in college where I learned how design could be used for storytelling and in an interactive web context. Learning more about digital photography and editing can also be helpful when working on projects or a portfolio. Lastly, learning at least a little bit of web design (maybe some HTML and CSS) can open up a whole different side of career opportunities if you find it's interesting to you.

If your school offers digital art take that and any art classes offered will help to gain skills.