Step #1: Click the "Accounts" tab on the left hand side, then click the account name (i.e. people by default) on the main section of the web UI.
Step #2: Click "View Users" on the right hand side of the web UI.
Step #3: Click the username you want to edit. Because of the permission level you're granted with Sidescale.com you will only be able to generate API keys for yourself.
Step #4: Click the "Generate Keys" button.
Your keys will be generated and appear midway down the main section of the web UI.