I want to report my roommate for what he did to me.
What kind of problem do you have with your roommate?
He stole my chips and put salsa on my bed
It really is not appropriate for a roommate to steal another roommate's food and then leave their roommate's bed a mess. Roommate's should give each other mutual respect and when one has a serious breach of etiquette stealing food, then it is okay to report that behavior to someone with authority. You have the right to keep your possessions in room safe and free from harm.
Yes, I'm going to submit a written complaint.
Right. It doesn't sound as if the two of you are very compatible. Perhaps he needs to go through the disciplinary process to learn his lesson.