Perform the following steps to import your project.
Step 1: Install git for Windows
It can be downloaded for free from git-scm.com.
Most settings available during the installation process should be compatible with Android studio. Just choose the settings you deem the most appropriate.
Step 2: Link git executable to Android Studio
Open Android Studio and got to Settings. In the Setting dialog open the page Version Control / Git. Here define the path to the git executable you have just installed.
Step 3: Get the Path to your Repository from Github
Go to the GitHub page and get the HTTPs path to your repository. For instance:
Step 4: Import the Git project to Android Studio
Go to Android Studio and go to Menu / VCS / Checkout from Version Control / Git
Paste the HTTPS path you obtained from GitHub in the previous step and click on [Clone].
Provide your GitHub username and password.
Now the project should be imported to Android Studio and you should be able to commit and push future changes back to GitHub.