The business details section of your account is accessible via Account - Account Details - Details
From this section, simply click Edit to enter your details:
You can add social profiles in the available fields, or by clicking add another link:
Please note that social profiles must include the prefix 'https://' e.g. https://www.facebook.com/bookwhenhq.
(don't forget to click Save changes when you're done!)
Once added, your information will appear in the footer at the bottom of your public page: