I am not sure if you are trying to create a remote branch from a local branch or vice versa, so I've outlined both scenarios as well as provided information on merging the remote and local branches.
Creating a remote called "github":
git remote add github git://github.com/jdoe/coolapp.git
git fetch github
List all remote branches:
git branch -r
github/gh-pages
github/master
github/next
github/pu
Create a new local branch (test) from a github's remote branch (pu):
git branch test github/pu
git checkout test
Merge changes from github's remote branch (pu) with local branch (test):
git fetch github
git checkout test
git merge github/pu
Update github's remote branch (pu) from a local branch (test):
git push github test:pu
Creating a new branch on a remote uses the same syntax as updating a remote branch. For example, create new remote branch (beta) on github from local branch (test):
git push github test:beta
Delete remote branch (pu) from github:
git push github :pu