First, you need to eat big and lift big in order to get big. For your eating, eat at least 25 calories and 1 gram of protein per pound of bodyweight each day. For protein eat foods such as: beef, chicken, turkey, fish, eggs, milk, protein shakes, etc. For carbs eat foods such as: bread, rice, cereals, potatoes, pasta, fruit, vegetables, etc. You should also eat a moderate amount of fats from foods such as: peanut butter, cheese, regular milk, butter, salad dressings, etc. Don't go overboard with it but a little extra fat will help give you more calories and energy to help you add bodyweight and build muscle. Eat a small meal every 2-3 hours. You also need to drink at least 1 gallon of water each day to help keep your body hydrated, help with digestion, rid your body of toxins, etc.
With your training you should train 3 days a week (ideally Monday, Wednesday, and Friday). You must give your body plenty of rest time to grow new muscle tissue. Muscles do not grow while you are working out; they grow while you are resting. Working out will stress and damage the muscles slightly. Then your body reacts by building up the muscles in order to handle the extra work and stress.
This is one of the best workout routines that I have found to add mass quickly.
Bench press:
1 set of 12 reps (warm up set)
1 set of 10 reps (warm up set)
1 set of 8 reps (heavy work set)
1 set of 8 reps (heavy work set)
Squats:
1 set of 12 reps (warm up set)
1 set of 10 reps (warm up set)
1 set of 8 reps (heavy work set)
1 set of 8 reps (heavy work set)
Dead lifts:
1 set of 12 reps (warm up set)
1 set of 10 reps (warm up set)
1 set of 8 reps (heavy work set)
1 set of 8 reps (heavy work set)
Military press:
3 sets of 10 reps (moderate weight)
You would do this workout each day you go to the gym.
Each workout you should try to add 1-2 pounds to each exercise (this is where the small fractional weight plates come in handy). It is easier to increase your weights in small increments (i.e. 1-2 pounds) more frequently then it is to make big increases (i.e. 10+ pounds) fewer times. Break down your big goals into several little goals and treat each one as a stepping stone towards the bigger goal.
This may not seem like much at first, but if you follow it for a few months you'll be able to add approx. 30 pounds of weight to each of your major lifts (bench press, squat, and dead lift) and at least 10-15 pounds of bodyweight.
You should go to the gym one day on the weekend to do some light work for your arms, abs and calves so these bodyparts are not neglected.
A sample weekend workout would be:
Barbell curls:
3 sets of 10 reps
Tricep push downs:
3 sets of 10 reps
Crunches:
3 sets of 50+ reps
Leg raises:
3 sets of 20+ reps
Standing calve raises:
3 sets of 10-15 reps
That is the workout in a nutshell. Focus on doing the big lifts done during the weekday workouts and eat as much good food as you can. This routine will definitely help you gain some size and strength.
After you have followed this routine for a few months. You should move on to a more advanced routine such as my 12 week workout program.
http://www.bodybuilding110.com/2016/05/12-week-workout-program.html