[swamp rat]

Looks like a dent to me too, it should be able to be popped back into place using a hammer off method, thats where a hammer and dolley are used and the hammer hits adjacent to the dolly and not right where the dolly is, if ya hammer right where the dolly is that can expand the metal, that expansion will lead to oil canning. there has been threads posted in the body section about "hammer on" and "hammer off" technique, its a good trick to learn if ya do body work, might give the search feature a shot with tho's terms and see if any threads pop up.

If its bad enough to oil can then you need to shrink the metal, there are different ways to do this, one is with a stud gun using a special tip, another is a shrinking disk on a right angle grinder, another possible way is with a tourch with a smaller welding tip. heat a small area at a time and it shrinks the metal. these are also a bit of an art forum, go slow.

If the dents arn't that bad, less that 1/8" you can always use some bondo, the purest body guy would not accept that tho.

All this said i'm no body man, just a guy thats trying to learning this stuff as he go's and getting lots of advice from people with way more experiance that me.