There are several steps in buying resale. ROFR is one of them. The basic steps are:
1. Make an offer and offer accepted or negotiated.
2. The agreement then goes to Disney for their approval, or ROFR.
DVC can, if they want, step in and buy the points for the amount negotiated. If they can buy low and sell high, they make money.
3. Assuming ROFR passes, purchaser deposits money with the tile company and the transaction goes to a title company which does the title search, etc. They also go to DVC for "estoppel" which verifies the points, makes sure no money is owed, etc.
4. Assuming everything goes ok, you then close
5. DVC member services then enters you into their computer and you can start booking.
6. Eventually you receive the title from the closing company.
If you are interested in resale, there's a few companies which specialize in DVC. The sponsor of these boards is one of these companies which has been used by many folks on the boards (including me). Give them a call and ask lots of questions. They also have some nice material they can email you which details the process a lot more.