Former EIC of a large HS newspaper here. The problem with writing about your school newspaper in your essay is that you’ll come off as one-dimensional. That’s already your biggest EC, but surely you have other impressive life experiences, etc. you can touch on. I think starting your own online paper is pretty cool. It should be noted on your Common App in your activity descriptions, and possibly on a relevant school-specific supplemental essay. But try to pick something else, lest you come off as bitter or one-dimensional.