On my website there is an option for customers to choose a plan they would like to purchase. Each plan is a different exercise regime designed for specific fitness goals. After a customer has chosen the plan, or exercise regime, they would like to pay for, I would then like the customer to be prompted with a following page asking if they are sure they wish to choose that plan. After this, I would like the customer to continue on to complete signing up, along with accepting the terms and agreement, and lastly payment. The catch is, throughout this process I would like the plan they have chosen to be saved in the system, so the whole time they are finishing up the signup and payment process, the plan they have previously chosen is preselected, so when the customer finishes the payment, the exercise regime they have chosen is automatically sent to them. How do I accomplish this?