GitHub ( http://www.github.com) is a cloud or web based Source Control tool & it is free for hosting open source projects. You can also buy hosting plans for your private repositories.
For one of my project I am trying to learn GitHub to use on windows computer. There is lot of reading material on internet , personally I dont like to read a lot. for people like me youtube is best place to learnstuff quickly. Here is one video for Novice github user on windows.