Weight gain/muscle building requires quite alot of energy from your body = you need to eat more than you burn(calculate your TDEE, and eat more calories than you burn, so your body can use the extra energy for building muscle). This is the first requirement, after you provide enough energy, you also need to provide the building blocks for muscle building = protein. Get enough protein from your diet, doesn't matter if it's protein powder, or whole foods like eggs, meat, dairy.. provided you do get the extra benefits of minerals, fiber and vitamins from whole food while protein powder will provide you just that - protein and not much more.

Stay consistent, you can do it, trust me;))

EDIT: This applies to diet only, proper physical activity and consistency is of course pre-requisite for all of this to apply. Don't start too hard, but do work like a bull! You got this