Configure your server.
$ ssh myserver.com
Welcome to myserver.com!
$ mkdir /var/git/myapp.git
$ chgrp grpName /var/git/myapp.git
$ chmod 775 /var/git/myapp.git
$ chmod g+s /var/git/myapp.git
$ cd /var/git/myapp.git
$ git --bare init --shared=group
Initialized empty Git repository in /var/git/myapp.git
$ exit
Add the remote repository to your existing local git repo and push
$ cd ~/Sites/myapp
$ git remote add origin ssh://myserver.com/var/git/myapp.git
$ git push origin master