If you eat enough, you will gain weight. Some people just need to eat more than others, since their methabolism is different.
Eat milk, lots of whole milk. That works for me when trying to gain weight.
You could also try a weight gainer.
Keep it simple like this, and then after gaining 15lb or so, jump into juice. Also, I take for granted that you BF is fairly low, around 14% or so.