How to Add a PPA to Ubuntu

How to Add a PPA to Ubuntu | OMG! Ubuntu!
Gitolite on Ubuntu: No admin key given

This adds the extra steps to bring in a ppa, install a new package, and reconfigure something like Gitolite3.

Replace ppa:snapy/ppa with your launchpad.
Replace gitolite3 with your package.

First, find a package you  want. I generally check to see if it's in the next release; easier to upgrade later.
https://launchpad.net/~snapy/+archive/ppa

From a terminal window:

    sudo add-apt-repository ppa:snapy/ppa
    sudo apt-get update
    sudo apt-cache gencaches
    apt-cache search gitolite3
    sudo apt-get install gitolite3

Then, after setup is finished, you can run the command sudo dpkg-reconfigure gitolite and it will prompt you to provide:

1. The user which gitolite will use
2. The directory which that user use to store all its files (gitolite config, gitolite managed repositories, etc)
3. (And the most important) the public key of the user whom will be the first administrator in gitolite, which you may either put the public key (just a single line starts with ssh-rsa or path to the file which contains the public key)