Go to the sign up page -> select the drop in membership for beginner/intermediate or advanced -> sign up your child -> once you have purchased the drop in, go to either the schedule on the website, or use the member app, which you will receive a login for after purchasing, and book into the class you want to drop in for. 

You have 1 week to book and use your drop in. After 1 week, if you have not used your drop in, you will lose that class.

Once you purchase the first drop in, you will be able to purchase additional ones through the drop in tab of the member app.