Setting up proxy in Nexus Repo Manager for Github hosted Maven Repo

Question

I am working on adding a proxy for Github Hosted maven repo. I have created the proxy and gave the remote storage url value as github url.

Anyone aware of how we can set up credentials for Nexus repo manager to talk to Github Repo. I am new to this stuff, so any help would be highly appreciated. I am guessing we might need to setup some generic user in github and created authentication token and use those for nexus to talk to Github?

Thanks in advance.