Bro,
Considering you already have a good workout routine in mind, a good diet is the most important thing you now need to put on some weight. Try to take in around 200g of protien a day, and that should be spread out over 5-6 meals. Try to get at least 500 calories out of each of those meals, and keep the carb intake at about the same or higher then your protien intake. All you have to do to accomplish this is read the food labels in the grocery store. Also, a large meal after you workout and before you go to bed will really help you put some mass on. Hope this helps. LATE
Considering you already have a good workout routine in mind, a good diet is the most important thing you now need to put on some weight. Try to take in around 200g of protien a day, and that should be spread out over 5-6 meals. Try to get at least 500 calories out of each of those meals, and keep the carb intake at about the same or higher then your protien intake. All you have to do to accomplish this is read the food labels in the grocery store. Also, a large meal after you workout and before you go to bed will really help you put some mass on. Hope this helps. LATE