Open Question: whats a good workout routine?

im signed up at a gym, but every time i go theere, i dont know what to do... can you just list like a routine for someone looking to just build muscle while leaning out? im 17 years old 5'6" 175 and i have lots of muscle and huge arms due to thats the only workout i ever do. i dont know what else to do, please, post your workout routine, Daily? Every other day? Thankss