Eat at least 15 calories per lb of body weight every day. Adjust up or down as you reasses weight gain weekly.
Eat 1g per lb of bw in protein. The rest should be fat and carbs. Eat veggies for health if you care.
Sleep 8 hours.
Pick a training program written by a coach and stick to it for as long as it gives you gains. You will see lots of dogma about all of this. There are push/pull/legs splits, full body, bro splits. If you are a true beginner my advice would be to try "starting strength". It's a full body 5x5 program and will give you HUGE progress in your first year. The focus is on compound barbell movements, you can add isolation later if you want.
If you're still lifting and posting a year from now let us know.