Perhaps you aren't aware of this, but Git is a distributed VCS. Thats essential to your understanding. OTOH SVN and CVS are centralized. You can still have a central repository in Git, and if you do, your users will need to be able to log into that server using SSH or HTTP access, look it up. Generally speaking, Git depends on the server's authentication.
So to make a git repo on a Debian or Ubuntu server for centralized use:
# apt-get install git
# cd /var/git
# git init --bare myreponame.git
# adduser <username> as needed
At this point you have an empty repo. To clone it to your desktop Debian or Ubuntu:
For SSH connections: look up ssh keygen and set up a passwordless connection to your server- keygen and sharing is only two commands.
To clone a repo:
$ git clone <server>:/var/git/myreponame.git
$ cd myreponame
Now you can add files and directories... when you have used git add and git commit, then you can use git push to push commits to the central repo.
- There are non-bare repositories, you must read up on this, use the standard Git references, just Google.
- Warning a "shared repository" is not what you think from the name.