Build Fitness program website

I am looking for a web designer to create a fitness program website where clients can purchase our monthly workout program. The website will be very straightforward, featuring basic images and videos of the trainer, an overview of what the program offers, and details about what members will receive. The website header will only have three navigation options: Program, About (trainer information), and Results. One of my biggest questions is what happens after the website is built. I would like to be able to update the monthly workout programs myself. For example, once a client purchases the program and continues their membership, how can I upload or edit the workouts they'll receive each month throughout the year? Thank you for your time. I look forward to hearing from you and hopefully working together. If your interested, Please inbox me and I'll shoot you a example of how I want it to look.