If you're eating more calories than you burn, you'll gain weight. Assuming you're eating a reasonable amount of protein, and are providing stimulus (i.e. working out), you'll gain muscle. No need to make it much more complicated than that when starting out. Bodyweight workouts can be incredibly difficult, especially if you have access to a pull-up bar and/or rings. I wouldn't worry about a target weight, just focus on slowly increasing your weight and making sure you're moving in the right direction.