Your body builds muscle naturally in response to your physical activity. This does not happen overnight. But you'll be well on your way to "bulking up" if you are consistent towards workouts.
First of all you have to decide on the exercises to be done each day. Some exercises focus on a specific muscle while other exercises are helpful for several muscles workout at one time. The important thing is to make sure each muscle can rest for at least a full day before exercising it again. So, you should do a full-body weight training routine, every other day (with cardio exercise in between) or you can alternate different muscle groups like arms exercise on one day, legs on another day, upper back and chest on next day and so on.
Body muscles grow during rest. If you do not give your muscle adequate time to recover, you'll be directly interfering with the muscle building process. When you lift weight, you put stress on the muscle to an amount that it breaks down at the cellular level which results in increased protein synthesis and produces thicker muscle fibers. This process begins 2 – 3 hours after the workout and lasts up to 24 hours. If you put stress on the muscle before this process is complete then you break down the muscle fibers before they have had a chance to rebuild and hence it can have undesirable effects.
You should learn how to do exercise properly (the extension of movement, correct stance and proper posture, etc) as this will not only reduce the effectiveness of the movement, but also increase the risk of injury. So, try to begin the exercise with light weights. Practice will improve your form. For muscle building process, you need to stress the muscles, so till the final rep of your final set, your muscle should be exhausted. You can add one or more reps if you are in good form. If stress on muscles is less then you need to add on some weight.
For effective muscle building you need to give your body the proper building blocks. Don not eat too much junk food. You can have supplements which can give you energy and aid in muscle recovery and repair, but, they should be taken in conjunction with a consistently followed exercise regimen and a proper diet. You should increase the amount of complex carbohydrates and proteins in your diet like egg, low fat yogurt, and whole grain carbohydrates like oats and whole-wheat bread. Try to avoid sugary and processed foods as they interfere with the glucose levels and immune system. You should drink a lot of energy drinks, water and juices during exercise to avoid water retention from the body. Protein drinks can also be taken after workouts to repair and rebuild lean muscle tissues.
For better results you should change your workout schedule every 3 – 4 weeks to avoid your body from adapting to stress. This can be done by increasing weight and changing exercises.