I am having trouble in Magit with step number 5 and step number 7 to create a new repository. If they exist, what are the interactive function equivalents (please) for steps 5
Magit does not provide any commands to interact with Githhb. You'll need to write your own command, around call-process and curl, or with gh.el which wraps the Github API.
To add a new remote, type M a in the Magit status buffer.