Step One

Checking for existing SSH key
Open Terminal and Enter ls -al ~/.ssh​ to see if existing SSH keys are present and Check
the directory listing to see if you already have a public SSH key.

Step Two

Create the RSA Key Pair
The first step is to create the key pair on the machine. Open Terminal and enter
ssh-keygen -t rsa

Step Three

Store the Keys and Passphrase
Once you have entered the Gen Key command, you will get a few more questions:
​

Enter file in which to save the key : This should be the location where you want your key to be saved — You can press enter here to move to next question.

Enter passphrase (empty for no passphrase) : It’s up to you whether you want to use a passphrase. Entering a passphrase does have its benefits.

The entire key generation process looks like this:

The public key is now located in your preferred location (id_rsa.pub) The private key
(identification) is id_rsa