AdamGB is spot on.

If you want to gain muscle you are going to have to eat a lot more than you currently do. For example if an 70KG man wants to be 100KG he has to eat like a 100KG man. Although I would say that a man who has quickly risen from 70kg to 100kg would be a poor boxer at 100kgs...

To build muscle, you muscle need to be stressed and then will repair themselves after, a combination of factors will affect this - AdamGB has gone over the foods, but I'd add that you needs as much rest as you can - you body repairs itself when you are asleep.

I have legs like a chicken - not sure if there's a gram of fat on them! I seriously trained for 1.5 years and this hardly made a difference - this included training legs once a week including calf raises, squats and leg press. I also did a course of Test in this time which made a slight difference, but hardly noticable. If you want bigger muscles then you need to train your muscle with heavy wegihts and low reps,. I'm pretty sure that I'll be stuck with these skinny calfs for the rest of my days.