Lift the basic compound movements (squats, deadlifts, bench presses, dips, chinups/pulldowns, overhead presses bent over rows, ab work (crunches). Always do your legs/hips where most of you muscle is. Squats/deadlifts do more to add muscle to one's body then any other exercise. Forget the concentration curls, skull crushers or other "finishing" exercises until you've done well with the basic foundation building compound lifts. Do the lifts 2 to 3 times per week with 2-3 sets of 8-12 reps. Try to add a bit of weight every workout but only after you've made all your reps in all 2-3 sets. Work hard not long. Give your muscles a reason to grow. Allow 48 hours of rest before your next weight workout. Do the same workout every time so you get proficient at the exercises. You'll get stronger quicker as well.
Eat 5-6 small meals per day. No junk, sugar etc. just good quality whole foods. Proteins, vegetables complex carbs etc. Don't even think of a fad diet. Let your hunger tell you when it's time to eat. Eat as much of it as you can (without getting fat). Drink lots of water as well. Some may argue with me but lay off the supplements. Your literally flushing your money down the toilet. Good old table food can build lots of muscle.
You've got to sleep well. Your body repairs, recovers and grows while you sleep. If you can get at least 8 hours per night do it.
Add cardio 2-3 times per week. It will keep you in condition so you can get through your workouts, help keep fat away and help with recovery.
If it can work for a 43 year old from the suburbs, it can work for you!
It's not rocket science, just common sense, discipline and hard work.
Lift well, eat well, sleep well = growth
God Bless!!!