Q: where to start
A: since i have no repo locally, so get one from remote first

 @gaia-> gh repo list
 gfoohub/foo                testing  public  13h
 gfoohub/gfoohub.github.io           public  1d

 git clone ssh://git@github.com/gfoohub/foo #clone remote to local

@gaia-> cd foo/
@gaia-> git remote #now it show remote
origin

Q: Adding Remote Repositories?
A:
git remote
git remote add 2ndrepo ssh:git@github.com/gfoohub/foorepo