I get asked something like this at every convention and often through email or DMs: "Could you give advice on pitching ideas to companies?"
Presumably, because I've been in a position to be on the receiving end of the pitch process. Well buckle up, we're going on a short ride! This advice is free and it's relatively simply to follow. Your mileage may vary (so many car metaphors), so I hold no responsibility here.
#1 - Check their website to make sure they accept submissions. Some will open submissions from time to time, so you may have to wait a bit.