Make sure you have installed the git and have received the github invitation
Go to the root path and open your bash cmd
write the following command
git clone https://github.com/noaRricky/Uncertainty.git # download the whole project
git fetch # provide your username and password to access the project
git branch <name># build your new exciting branch
git checkout <name># dive into your branch and write your code
...
git push origin <name># after you have add and commit your contribution, don't forget to push the remote