There several simple steps that can help you build muscle and here are the most basic. Be sure to eat as many grams of protein throughout the day for every pound you weigh; 1 pound of body weight = 1 gram protein. Eaten in several small meals throughout the day increases your metabolism and is the best way to get your daily protein, but you can also take protein supplements. Because you will be expending energy, you will also need to consume enough carbs to fuel your workout and build muscle.
Get good quality sleep and alternate days you workout so your body starts building muscle. Focus on your core muscle groupings and find your center, build your full body workout from there, adding more muscle groups as your strength grows.