How much lose weight in 2 months? (Health and Medicine, Health, Sports)

Hey..

So I’m 18/w, I’m 1.67m tall and weigh around 48kg.

I want to work out my butt a bit and gain some weight in general because I don’t want to look like a leek anymore. What should I watch out for?

Does it matter what I eat? And how much weight should I gain in order to be able to build more muscle mass? In the end I want to weigh between 50-55kg.