When you sign up, you will receive a coupon code. On your first booking after registration, apply the coupon code. When you complete the reservation and send in your statements. (doesn't matter the order)

Hotels will deposit the free night into your account. The value of the free night will be based on the booking you made. So you have pay for at least one night to receive a free night. Plus you have to document that you have had activity in other loyalty programs.