You can simply edit your configuration file in a text editor.
In the ~/.gitconfig
you need to put in something like the following:
[user]
name = Uzumaki Naruto
email = [email protected]
[github]
user = myname
token = ff44ff8da195fee471eed6543b53f1ff
In the oldrep/.git/config
file (in the configuration file of your repository):
[remote "github"]
url = [email protected]:myname/oldrep.git
push = +refs/heads/*:refs/heads/*
push = +refs/tags/*:refs/tags/*
If there is a remote section in your repository's configuration file, and the URL matches, you need only to add push configuration. If you use a public URL for fetching, you can put in the URL for pushing as 'pushurl' (warning: this requires the just-released Git version 1.6.4).