I hope I don't offend anyone with this questions but if a person was born blind what do they dream about?

Only they can tell. I think it would be worthwhile to ask them, since none of us on this site is blind if we can read your question.
Dreams if blind. Dreams are constructed from the brain's attempt to create a reality based upon normal experience. A blind person from birth has well developed hearing, touch, smell, etc. And will construct a dream from these components. Oliver sachs has some good discussion about these aspects of brain function.