Firstly, check whether you already have an SSH key pair set up on your local machine. Usually, the SSH keys are stored under a .ssh directory under your home directory:
$ cd ~/.ssh/ && ls -ahl
total 116K
drwx------ 2 dli dli 4.0K Jul 10 10:39 .
drwxr-xr-x 94 dli dli 16K Sep 12 18:59 ..
-rw-r--r-- 1 dli dli 151 Mar 6 2018 config
-rw------- 1 dli dli 3.2K Oct 2 2017 id_rsa
-rw-r--r-- 1 dli dli 740 Oct 2 2017 id_rsa.pub
-rw-r--r-- 1 dli dli 80K Sep 12 19:08 known_hosts
If you see output similar to this, then you already have an SSH key and can skip ahead to the Adding SSH key to remote server section; otherwise, carry on with creating an SSH key.
A key is basically a very long, random string that acts in place of your password. When you associate a key with a server, you're able to authenticate to that server using that key. Therefore, you may have multiple keys, each one associated with a different server.
This also means that you can create a new key for this exercise, even if you have a key already. But generally, most developers have one key for each development machine.
This also means that you can create a new key for this exercise, even if you have a key already. But generally, most developers have one key for each development machine.