Sport Loop watch band

First, slide the free plastic piece just below the 5 plastic velcro ovals. Fold the band over at the free plastic piece and press the Velcro so it attaches. The free plastic piece should now be trapped in a loop of band. Now place the band flat on a table with the part of band that has the Velcro attached on top. Keeping the band flat, turn the band so the loop end is facing away from you and the end with the plastic piece attached toward you. Take your watch, and orient it how you will want to wear it (which side do you want the buttons on). Slide the free plastic piece trapped in the loop into the slot at the bottom side of the watch until it “clicks”. Now take the remaining end facing you and loop it around and slide it into the top side of the watch.

Here’s a reference link: https://support.apple.com/guide/watch/remove-change-and-fasten-apple-watch-bands-apd3cc13d48f/watchos

if you’re still stuck, YouTube surely has a how to that will help

Using your picture on the left you slide that in on one side of your Watch and you connect the other piece just to the right to the other side of your Watch. You will need to slide it down. Then you put your wrist through it and use the piece at the far right to tighten it.