Good job. Modern cars' belt systems are actually pretty easy to work on once you know how. One belt, one tensioner that's spring-loaded, usually. But, there are often "idler" pulleys as well so check those also.
When I was 17 or so I didn't know how even to check the oil on a car. Then my sister and I bought a used car together, and the first thing that went wrong was the brakes. There was a repair guide in the trunk, so I followed it and changed the front brake pads. That was almost 30 years ago and now I do all my own work, and some for others. Meaning, you can learn how to do this stuff if you want to.
Oh, and, pay yourself with a treat of some kind. You did well. Tools are fun.