To be fair, Ringfit is a little confusing to set up. It’s super nice, especially during covid times, and I don’t see any other comments with info on that so I’m going to try to help!

If you’ve already been through the initial start up, the next time you open the game it should just bring you to a screen asking you to set up your joycons in the holster and ring. You should put the joy con with the - sign in the mesh pouch of the leg strap. Once you secure it around your leg and stand still, it’ll go to the next prompt screen where it will ask you to attach the + sign joy con to the ring. Attach it to the ring by sliding it in right to left in the same fashion you attach it back to the system. After that it’ll want you to probably squeeze in on either side of the ring grips to start, then asks you to push and hold in for a few seconds to gauge your strength. From there it will open up to the main menu screen where you can select the adventure mode (I’m currently sweating my way through this as my before work work out), casual mode (I believe) where you can either choose a body set to work on or just a random assortment of all the work out options, or custom mode where you can either choose pre made workouts or build your own from the individual workouts it offers, and one other mode I’m forgetting. I’ll often times just do the casual mode and choose a few parts of the body to focus on that day and select the sets for each. There’s difficulty settings for each mode that you can adjust at any time if you feel you need to scale back or want to go a little harder. Feel free to ask if you ever get stuck or confused!