Create new GIT repository

on git repository server

ssh git@git-server
mkdir testapp.git
cd testapp.git
git --bare init --shared=group
chmod -R g+w .

on local machine, in any folder

mkdir testapp
cd testapp
git init
# create a file with a few lines.
git add .
git commit -m "initial commit"
git push ssh://git-server/home/git/testapp.git master

don't forget to add each user to git group.

Reference

Git magic, a very comprehensive tutorial, almost like SVN's redbook.