This is a repository for NuPack packages. In the longer term, we’ll have a nice Gallery site with all the bells and whistles, but for now this is what our public feed (http://go.microsoft.com/fwlink/?LinkID=199193) is driven off.
Here is what you need to do to contribute packages.
Fork the nupackpackages repository
Note that this is a different repository from the NuPack repository, which has the sources for the NuPack engine. This one just contains packages.
Just go to the Source Code repository and create a fork. If you’re unfamiliar with Mercurial, start here.