How To Gain Body Mass?

hai, I am 28 years old guy, with lean body like ectomorphs kind of body types, and having 50 kg of body weight. I want to increase my body weight and muscles .I have started gym from past 3 months. There is not much change is happening .I am planning to take a weight gainer and whey protein together. I believe that both of this will help me to increase weight and muscles. And i don t have any other problems other than this on my body. Normally fever will come once or twice in a year. please guide me for this . Thanks.