Easy day. Put together a basic, solid lifting routine centered around the big compound movements(squat, deadlift, bench, pullups, etc.) and hit it. Get at least a couple months under your belt doing that before you tryand jump into one of the mroe advanced routines here.
Increase your calories, try to eat clean but don't obsess about it. 5-6 meals a day, 1g of protein per pound of bodyweight, plenty of good carbs(screw the low-carb shit till your bigger and want to cut), plenty of water, plenty of sleep. Learn how to lift properly before you try to push the weights up. Always pay attention to your form. Go this route(or something similar) and you should see really good gains in six months or so.
I had been lifting for a few years prior without gaining any weight(maybe 5 pounds), when I changed my diet in early 97. That's all it took, and I gained 20 pounds in 4 months and stayed pretty lean(12-14%ish).