To connect a self-booking form in Appointment Reminder to a Contact Reach campaign, you need to use the Assign Contacts section inside the properties of your self-booking campaign.

First, open up your Self-booking campaigns list. Then select which campaign would you like to connect into a campaign in Contactreach. Click the Actions menu button, then click Properties. 

Once you're inside the Properties, open up the Assign Contacts section

You can then select the Contactreach campaign that you want to integrate with the Self-Booking Form in the Select CR Campaign dropdown menu. After selecting one, hit Save.

What happens here is when a customer sets an appointment on the self-booking form, they will also be subscribed to the connected Contactreach campaign.