Confused about Bike tires rims width? Continental Grand Prix 4-Season fitment

My bike is an older Jamis Satellite, beginner bike. I don't ride that often but plan to now more so this summer.
Instead of buying a new bike, I decided to get new tubes, tires, tune it up. This is one of the videos where I found so much content that it would make your head spin. So, this video is a synopsis and perhaps answers I couldn't find.
Give me a thumbs up if you find it helpful or share your comments or questions below. Biking community appears to be very vocal so I know you're not shy.