Github adding a repository as a fork from an existing clone

So I have a git repository that I cloned from an upstream source on github. I made a few changes to it (that are uncommitted in the master branch). What I want to do is push my changes onto my github page as a new branch and have github still see it as a fork. Is that possible? I'm fairly new to git and github. Did my question even make sense? The easiest way that I can think of (which I'm sure is the most aroundabout way), is to fork the repo on github. Clone it locally to a different directory. Add the upstream origin repo. Create a branch in that new forked repo. Copy my code changes by hand into the new local repo. And then push it back up to my github. Is this a common use case that there's a simpler way of doing it without duplicating directories? I guess I'm asking here as opposed to SO since I'm on linux using command line git and the people here give better answers imo =]