Either search the WEB on how to refinish a hardwood floor, or stop by a Home Center and spend a few $$$ on a good how-to-book. In short, you'll need to rent some heavy-duty equipment that is not so easy to use for a first-timer. If you aren't careful or aren't TOTALLY understanding of how the equipment works (for you and against you), you will damage the floor.
I'd consider getting 3 estimates. Then, price out the costs from your end as well as your time and see if it's worth it. Sometimes, it's $$$ well-spent to hire a Pro. (In your case, it may be so.)
My best to ya and hope this helps.
Jay J -Moderator
PS: God Bless America!