When someone visits your website and takes an action, the Facebook pixel is triggered and reports this action. This way, you'll know when a customer took an action after seeing your Facebook ad. You'll also be able to reach this customer again by using a Custom Audience. 

To add your Facebook Pixel to your website, please email the complete code details to the Aro Support Team (support@arosoftware.com).

This guide from Facebook will show you how to create your Facebook Pixel. It will also show you how to find the code details to send to our Support Team