I tried following this doc...
...but unfortunately the "initialKeyFileName" step is not explained.
It says on the top:
The linked article is great, should be no problem to follow it.
Sparkle Share – Git server installation in Ubuntu 10.04
I am starting with an empty Ubuntu server 10.04 with just openssh installed. I assuming that you can access you server from http://mydomain.com
Add user git
Make a key file in order to login without a password
Change owner and permissions on files
Add your server in client
I've create a document here about install git on Debian box, i think that you may follow the same step on a Ubuntu