This is a straight forward list of steps to connect to github with a ssh key instead of user/password.
I am using Linux on my development machine so things are quite easy with ssh.
STEP 1: Create a ssh key
# ssh-keygen -t rsa -b 4096 -C “email@example.com”
STEP2: Add the key to the authentication agent
# ssh-add ~/.ssh/id_rsa
STEP 3: Display the public key
# cat .ssh/id_rsa.pub
STEP 4: Copy the public key to the clipboard
STEP 5: Import the key to the github.com account
Click on the profile icon -> Settings
Then under “SSH and GPG keys” in tge SSH Keys paste the New key from the clipboard
STEP 6: Clone a private repo using the new key
# git clone firstname.lastname@example.org:voinageo/myapp.git
All done , from now on any git operation using the private repo from github will no longer ask for user/pass but will use directly the secure connection using the ssh key.