I think that's fantastic. Getting some professional writing experience while you are in high school will look awesome on a college application. I am sure you are a great writer. When I was in HS, I tested out of all pre-reqs for English in college. I haven't taken a writing class since high school and I am a successful professional writer. It absolutely can be done.

Just make sure to pay attention to some technical things like citations and references, which you can easily Google the latest style guides to do correctly. If you are writing online for a media outlet or blog, typically that stuff doesn't matter.

Some colleges offer one-time, like 90 minute classes that are for "business" writing. They cost like maybe $50, pretty inexpensive. I would look into one of those just so you learn the things to look out for.

I'm sure you will be successful if you want to be.

Good luck! (My up and coming competitor!)

Seesaw