Carole, bumping is something we do if we want to draw attention back to a certain post that's no longer easily visible. E.G. if we posed a question for Angie but it moved off the main forum page before she could see it, you'd go back to the post and add a comment saying "bumping" so that it would reappear at the top of the forum and could therefore attract more responses.
It's not a stupid question, btw.