The server name is your DNS or ip.
Usually this is your setup.
<Domain>/<gitServerName>/<gitRepositoryName>.git
Say your domain name is
foo.com, git server name is git, and repo name is test.
Then you'd have:
http://foo.com/git/test.git
You can replace foo with an ip of your server.
If you don't have an external facing server, on the other hand, you would need to set up some method of hosting.