It's from

Step 1: Check for SSH keys

$ cd ~/.ssh
$ ls -al
#Lists the files in your .ssh directory

Check the directory listing to see if you have files named wither or If you don't have either of those files go to step 2. Otherwise. you can skip to step 3.

Step 2: generate a new SSH Key

To generate a new SSH key, copy and paste the text below, making sure to substitute in your email.
The default settings are preferred, so when you're asked to "enter a file in which to save the key, "" just press enter to continue.

$ ssh-keygen -t rsa -C ""
# Creates a new ssh key, using the provided email as a label
Generating public/private rya key pair.
Enter file in which to save the key (/Users/you/.ssh/id_rsa): [Press enter]

Next, you'll be asked to enter a passphrase.

Enter passphrase (empty for no passphrase): [Type a passphrase]
Enter same passphrase again: [Type passphrase again]

Which should give you something like this:

Your identification has been saved in /Users/you/.ssh/id_rsa.
Your public key has been saved in /Users/you/.ssh/
The key fingerprint is :

Then add your new key to the ssh-agent:

$ ssh-add ~/.ssh/id_rsa