If you want to do it yourself, take off the interior piece, find a wooden rod, a rubber hammer, and go at it until the dent is out to your liking. Then buy body filer, fill, wait until dry, sand until it's level and smooth, prime it and paint it, of course it won't be perfect, but it's better than nothing. Other wise you can do all that then let a shop paint it, most likly they will do the whole door.
I suggest you call "Auto Dentist" They are on Bentley road, they do small things and usually are good with price, and they come to you. Almost every dealer use them to touch up pre-owned cars. Good luck.