https://help.ubuntu.com/community/Git
There is a local machine and a server which will act as a Git Server.
On the git server:
sudo apt-get install python-setuptools git-core gitosis
On the local machine:
ssh-keygen -t rsa
scp the public key to Git Server at /tmp/pub-key
On the git server:
sudo -H -u gitosis gitosis-init < /tmp/pub-key