I will explain the solution :
Download Github For Windows client and install it.
After the client is successfully installed, connect it with your Github account. It should be easy, just follow the wizard.
Then you should add git.exe extension to your "Path Variable". The path you will add will probably look something like this: C:\Users\Your_Username\AppData\Local\GitHub\PortableGit_ca477551eeb4aea0e4ae9fcd3358bd96720bb5c8\bin
Alternatively , if you don't want to add to environment variables. Open the android studio and navigate to : Settings -> Version Control -> Git In text box next to "Path to Git Executable" you will see "git.exe" , just give it a full path like so : C:\Users\Your_Username\AppData\Local\GitHub\PortableGit_ca477551eeb4aea0e4ae9fcd3358bd96720bb5c8\bin\git.exe
Hope it helped you!
Note: For latest Github for windows versions some can find the git.exe under "...\cmd\git.exe" rather than "...\bin\git.exe".