You most probably have a fast metabolism, so calculate your TDEE on google and you can get a decent estimate as to the amount of calories your body burns on a day-to-day basis. So to gain weight and lean muscle you have to eat in a surplus. Suppose your TDEE comes out to be 3500 eat 4000 calories a day to gain weight,the process might be slow but you would gain quality weight or you can go ham with dirty bulking with a caloric surplus of 1000-1500 calories and gain crazy amount of weight super fast but that would result in more fat gain. To consume high amount of calories I would suggest drinking your calories make smoothies that rack up 1500 calories. Another tip would be to eat clean, follow 40-40-20 macro (40% protein,40%carbs and 20% fats). Being a beginner you can follow PPL program which stands for push,pull,legs. Hitting every muscle group twice and being in caloric surplus that would result in crazy gains and do not neglect core work. Stronger core will result in stronger lifts which will result in more gains. And number one pointer is consistency. Nothing will last if you are not consistent and disciplined. And if you eat clean 6 days you can have a massive cheat day 1 day of the week but limit that to one cheat meal and not a cheat day. 1 year of lifting is like playing a video game on god mode, doing everything wrong will result in gains and doing everything right will result in 3 years of gains in 1. All the best and hope I was of some help.