But I looked at my problem for hours and I really don't know how to start!
If you truly looked at the problem for hours, then you must have something that you find confusing. This is something you should tell us about, and it shows you thought about your problem.
Also, when we ask for attempts, people often think that we already want half the solution. This is not true. Attempts consists out of many different forms. You could include a specific question that's confusing you, an approach that doesn't seem to work, definitions or theorems that you're having problems with applying, a previous problem that seems to ask something related but that is easier, etc.