Issue with github deploying

Hi folks, I trying deploy my Hugo site and I use Hugo Docs instruction: There is example on Step-by-step Instructions (paragraph 6): git submodule add -b master<USERNAME>/<USERNAME> public
That made confuse me. What do I need insert USERNAME>/<USERNAME?
I’v attempt put: git submodule add -b master public
but then I obtain: fatal: repository ‘cosmos-factory/’ does not exist.
I have repository: http://cosmos-factory/

You should fill the <USERNAME>/<USERNAME> with your Github username.

For example:

git submodule add -b master public

Where ardianta is my Github username.

No, it doesn’t work

Have you create the <username> repo on Github?