Download MyFitnessPal to track your calories and macros.
Start at 15cals x Bodyweight in lbs. Adjust higher if the weight gain isn't fast enough.
Eat 1g/lb of body weight of protein. The rest of calories come from carbs and fat.
Sleep 8 hours every day.
Start a barbell lifting program. Google "starting strength" and stay on that for a year minimum. Squats, deadlifts, bench, row, OHP, pullups etc... many people work without a spotter. Here's a secret, if you can't handle the weight in a controlled manner than you don't lift that weight. If 225 x5 is unsafe then do 215x5 until you graduate to 225.