Wannabe Film editor, don't know what steps to take?

TLDR at the bottom.
So I’m going to the University of Illinois and am a Media and Cinema studies major. However, after reading more about the program I realized that it is not really about producing films, it’s more studying them. I don’t really know the exact career I’d like to go for, but I’m leaning toward editing. Honestly I’d love to just make movie trailers all day but I don’t know a lot about that career.
Anyways I was thinking about majoring in Advertising and minoring in cinema studies and then doing a grad film school. Is that even possible or do film schools only accept film undergrads? I’m just so confused and not really sure who to talk to.
TLDR- I want to be in the film business but want to major in advertising and go to grad school for film, is that possiblle?