You can add support links to your storefront, where customers can contact you should they need assistance.
To make the phone number clickable in the support dropdown, you will need to include the following code:
For example, here is Word Geeks' phone link: <a href="tel:1-888-614-3357">1-888-61-GEEKS</a>
For a Help Center or FAQ page to be clickable:
<a href="YOUR.WEBSITE.LINK" target="_blank">WEBSITE NAME</a>
For example: <a href="http://wordgeeks.zendesk.com" target="_blank">Help Center</a>