Look into taking Phopsphator, it’s a legal form of a steroid somewhat, I used it when I was in track, I gained 13 pounds of upper body muscle in 3 months.
for workouts I would recommend doing basic things for big muscles, try doing bench press, skull crushers, curls, squats, etc. The best way to gain muscle is to stay committed to a few muscle groups
*The only downside I found in phopsphator was that I got acne, and it’s kinda expensive.