Permission error when I send a new project on GitHub

Hi all,
I have already sent a project on GitHub with a SSH key and everything went well.
Now I created a second project, but then he tells me every time this error when I type the command “git push origin master”

ERROR: Permission john/Rails-project.git denied to john/Rails-project.
fatal: The remote end hung up unexpectedly

Do you have an idea of the problem?

Thanks.

You need to first create the repository on Github before you can make pushes to it.
When you create a repo on Github the process concludes with a page that describes how to “init” and then “push”