Handball - looking for a training program

Greetings.

I am seventeen years old and currently compete in handball, standing at 6'1" and weighing approximately 172 pounds. I would appreciate your assistance if anyone could design a structured training regimen focused on increasing my vertical jump and building muscle mass, along with nutritional guidance since my current diet is quite poor. I previously attempted weightlifting, but I discontinued my efforts after three weeks because I lacked a proper program.

Thank you very much.