If you have installed Github for Windows and still got trouble when you tried to running command on CMD then here is a sollution to trouble.
Open this C:\Users\myusername\AppData\Local\GitHub\PortableGit_93e8418133eb85e81a81e5e19c272776524496c6\libexec\git-core in your windows explorer. Now copy this path.
Now go to Start –> Edit environment variable > search the System Variable “path” Edit the value. Add ; and the path you have just copied. Now you can run git commands on Cmd.
If you still have trouble that some DLL is missing then download Git from http://git-scm.com/
Now after installing this you can Follow http://stackoverflow.com/questions/3431361/git-for-windows-the-program-cant-start-because-libiconv2-dll-is-missing to solve the issue for missing DLL.
Thanks for read my post