how does radar work?

Hello,
i know till now i have always been the guy who has been asking for pictures and stuff like that, or making jokes and stuff like that. But i actually have a question today(a serious one)
Can someone explain to me how do radars work?(please little more then the key basic about radio waves and transmitters/recevier, i know a little bit) i am intrested in how the phased array radars, doppler radars, SAM and AShM radars work? ie. how they identify the target and stuff like that. Also there is a way that you can avoid a doppler radar(by making a sharp 90degrees turn if i am right)
So if anyone is kind enough to share their knowledge that would be great.