pushing a branch without merging

Hi,
I'm managing a website with Git. I work on my local machine and push
changes to a bare git repository on a remote server. Then there there
is a hook to pull those changes in a directory with the live website.
I use the server only for the development version of the site and it
happens that when I'm working on a branch feature I want to show to
others what I'm doing.

So, on the local machine I can easily create a new branch, but I don't
know how to push what I modified in the new branch without affecting
the master branch.
What am I missing?