The paint is damaged, is it worth using your service? 
If the paint is only lightly scuffed with a faint mark that will polish out or has a very small chip in it which can be touched in then yes it probably is, if however the paint has been scuffed all the way back to the metal or has large cracks in it than a conventional body shop repair would be more appropriate.

Does the dent just pop out?
No. The dent is lifted gently and meticulously a tiny bit at a time until it reforms its original shape. Some larger dents have a sweet spot where some applied pressure will pop it out but you are still left with a lot of creases and crowns that will need a lot of work to level up.

So how do you do it?
The dent is pushed and manipulated from behind very slowly and gently until it reforms to it’s original shape, all PDR technicians have a variety of sprung steel bars with various tips and of varying length and shapes, these bars are all about gaining access to the back of the dent and leverage, a good PDR technician could remove a dent from your car perfectly with a your own car key if he had to, the tools we use just make it easier as a lot of dents are difficult to get to the back of.

I’ve seen a DIY dent "improver" kit can’t I just have a go myself?
You can but they're called an "improver" for a reason and in the wrong hands could potentially cause more damage. PDR is a complex and extremely difficult skill to learn, it takes many years to master and a professional will have thousands of pounds worth of tools at his disposal, something bought for ten or fifteen pounds on the internet won't even come close. If you can’t live with the dent and take pride in your car then don't risk making the damage worse and an expensive trip to the body shop, get it looked at by a professional PDR technician.