The switch backdrop button, well, it switches the backdrop. When you are in the market, you click on a horse to buy it. You can have unlimited horses in the stable. To take care of a horse, there is the care station. I didn't want to do more coding, so it just shows the brown horse to take care of. Try brushing the horse and putting a few accessories on it! When taking care of the brown horse, click 'train' to go to the grassy field. There, you can move the horse around and train it! You can also catch horses in the savanna, and it's the only way to get a unicorn. I ADDED RIDING!!!
The horse art isn't mine, it's Scratch's unicorn art. Any suggestions are welcome.