tips to get body

you already have a body. you just have to buff it. Eat exactly the same time everyday. Make sure you eat three meals a day with two or three in between meals ( in between meals means snacks). Take a nap. Sleep early. In one week you are going to increase your appetite and gain at least 1 kg in 2 weeks. That was an advice from my health doctor on me several years ago which i followed diligently and it worked. It takes discipline to be successful. If it still doesn't work, it's time to see your health doctor because you might be suffering from illness that you aren't aware of. Good luck!

are you a vegetarian or omnivores ?

You probably have a fast metabolism. As you get older it will slow down and you will put weight on.

Why don't you consult a physician? They'll tell you if you need to put on weight or not. How can we help you without knowing if you're a man or a woman, your age, weight, height?