I used to handbook a Corolla and conviced my dad to get it rust proofed each year ( i live in Canada, chill months results in ALOT of salt on the underbody). 9 being downs the road and subdue not a spec of rust. When my dad got his new G35, he rust proofed it on the 3rd day with driving it home! You can ordinarily go to a company that does rust proofing in your area. They’ll sterile and spray your car surrounded by and out to prevent any rust from forming. Some places even drill holes at the sides of you door and spray rust proofing surrounded by the plug it up. Its a really excellent thought whether your tiresome to make your car last or if your inane to sell it, rust proofing really retains the regard of your car. To get rid of the rust, you can sand it off and place primer over it. Question the rust proofing guys, maybe they know a better way to handle it??

sand rust area to get rid of most of the rust Thain spray with rust converting spray
it can be bought at most places they sell paint

it will turn reamaning rust black

now paint over this with 2 or 3 coats of touch up paint

take out it by sanding it off to a charming go up and then bondo and primer to keep it from appearance back. then paint over bondo.

Sand the rust off. Then fill in and paint the car.