Gain weight?

you definitely have to gain weight.you should be at normal weigh of the height of 1.77 is to be 67-75 kg.But i think that is normal if you are thin(no offence), but maybe i'm wrong.The best way to gain weigh is to eat more and more.Second not to spend your energy so much eat more food that make you gain weigh.I don't have so many suggestion but you can search on internet how much calories have the food you normally eat and how much you eat from that food. Make a daily plan what you will eat,how much calories you eat daily, look how ,much you weigh every week or every mount.If you gain weigh with a food that have more calories than other food keep it up.But also be careful with your health and what food you eat.