If you are starting from nothing (no existing `git` or `git-annex` repository) and want to use a server as a centralised repository, try the following steps.
On the server where you'll hold the "master" repository:
server$ cd /one/git
server$ mkdir m
server$ cd m
server$ git init --bare
Initialized empty Git repository in /one/git/m/
server$ git annex init origin
init origin ok
server$
Clone that to the laptop:
laptop$ cd /other
laptop$ git clone ssh://server//one/git/m
Cloning into 'm'...
remote: Counting objects: 5, done.
remote: Compressing objects: 100% (3/3), done.
remote: Total 5 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (5/5), done.
warning: remote HEAD refers to nonexistent ref, unable to checkout.