Yeah you caan use water. I've even used dish soap before.
You can pull at least most of that out. Not much you can do if you have sharp creases, but I guarantee you can make it look 100x better. I've been meaning to ask, why is your avatar pic sideways? One day I was staring at it for a couple minutes before I figured out what the hell I was looking at....
i took it with my phone and thats how it came out on the computer a i dont no why
Here's a trick you can try.
With a hair dryer, and canned air; heat the area with the hair dryer for more than one minute. Then immediately holding the canned air upside down spray the canned air over the entire area of the dent. Coat the dent generiously. Wait for the frost to completely melt, and then clean the surface.
some body shops use dry ice and a heat gun and it works much better a lot colder and a lot hotter. see it done. can you get behind the dent were is it? post a pic and im sure i can give you a way to make it go away. so you cant barely see it