I would like to set up our referral program in the following way: if our members can get their friends to purchase a membership, the member would get a free 60 min massage. How would this be set up?

To set up this type of referral campaign with InviteBox you will need to choose the Goal Based Reward campaign, and put one conversion as a goal on the setup pages.  You will also need to place the tracking code on the page that your customers see after a purchase.  so how this will work is when your campaign participants attract new customers that place an order on your website they will automatically receive an email.  This email, designed by you, will contain a unique code for them to use to claim their reward.  An alternative is to ask them in this email to contact you to schedule their 60 minute massage.