git clone http://github.com/mono/bitsharp.git
This command allow you to get all source and all history. If you want to deelop create an account on github and make a fork.
git checkout bitsharp-0.90
This should be used if you want something that works and do not require specific features/fixes which are only available in SVN. This is the recommended starting point for using MonoTorrent.
git checkout master
If you require features or fixes which only exist in SVN, want to develop new extensions/features or just want to help test the latest iteration of MonoTorrent, you should use the code from here. Bear in mind that occasionally SVN head can become unstable so if you run into issues either try the latest stable release, or just check out a slightly older revision of the code.
If you want to send patch, you will have to work git. So here are good Tutorials:
http://help.github.com/
http://linux.yyz.us/git-howto.html
http://groups.google.com/group/pinta/web/git-tutorial?hl=en