It only requires three steps

1 Create a new SSH key

ssh-keygen -o -t rsa -C "email@example.com"

2 Copy the content

Just check the output of the first command, it would add a path of the ssh key .pub file, now just copy the content:

pbcopy < /Users/<your-user-name>/.ssh/id_rsa.pub

3 Register a new ssh key in GitHub

You can add the content of the key in the form of this URL

https://github.com/settings/ssh/new

it is done... happy coding!