eat a lot of lean meat, cooked beef,lamb etc. drink plenty of water ( real water not flavoured water or fizzy drinks or energy drinks) if your working out which i recommend, add protien shake to the water, or drink a mix of milk+protein powder.
eat natural foods with no added shit, for example, boring plain food with no added additives like sugar etc
examples of this could be:
breakfast:
oats+milk (add fruits for flavour and sweetness or cinnamon)
boiled eggs ( not fried)
lunch: protein bar or salad with tuna, try to get tuna with sunflower oil, the fat will help you.
dinner:
BOILED chicken breast or fish fillet haddock mackerel etc with SWEET potato (purple potato)
bedtime: cottage cheese and protein shake.
doing all the above + excising will help you increase your weight, you could always just eat plenty of junk fried food and get fat, but if you want real weight with muscle then do what i`ve mentioned and it will be fine.
remember you do not need to go to the gym or own a gym to get fit add weight or be healthy!
staying at home and working out is easy too, stick to the diet, do 20 press ups 3 x a day to work your upper body,
do 20 sit ups 3x a day to work your core
do lunges at home or squats with something with your hands ( a full milk bottle or something weighing 1kg+ would be perfect)
i hope this helps and good luck with your goals m8!
p.s you can not grow any taller after age of around 20+