Hi. No sticker at the back could indicate that it's had a rear-ender and respray. Any other evidence?
As for the rust spots, sand them off back to the metal, and mask up around the area. In light coats, gradually build up the primer and allow to dry fully. Then, rub down with some fine grade wet and dry paper, and clean to get rid of any dust. As for the top coat, once again build up in light layers, and be very patient! Best done out of breeze and direct sunlight. Once complete, rub down again gently with damp wet and dry paper, and leave to harden before polishing.
That's the rough guide- I'm no expert! Lots of the guys on here will be able to fill you in on the finer detail.
Good luck!