No one ever said it was going to be easy.
Figure out what your goals are, and adjust your food intake to suite.
In order increase lean mass, you have to provide your body with ample nutrients to grow. Proper fats, carbs, protein. In order to grow its important to provide your body with a caloric surplus. Figure out what your BMR is, and figure out your daily caloric needs in order to create lean mass. Keep your protein high, and from lean sources. Don't get to crazy, but about 1-2g per pound of mass. I find keeping a log very helpful in maintaining discipline.
Everyone is different, and everyone responds differently. Its all a matter of trial and error.
Good luck to you.