Jiddy... that's a crazy diet!!!! Great for 6'8" - 325 lb NFL tackle during training camp, but I think a 125 lb guy would get sick on it!!!
Diet's by FAR the most important thing that you'll need to be consistent at to be successful in any fitness endeavor. 75% of the game is diet. In your case I'd recommend 3500 cals/day for starters w/ ATLEAST 200 g of protein divided into 5-6 meals. That's roughly, 700 calories and 40 g of protein per meal. Don't be afraid to eat macdonalds' or other crap once in a while. Supplement w/ a good quality multivit., EFAs (high potency fish oil), and anti-oxidants.
There will never be a consensus on what training modality is best. Therefore, its upto you to figure out what works for your body type. You'll also have to factor in things lifestyle, and how well you adhere to your diet. Guys like Carlito see results because their diets are spot on and they're very consistent. IFF you can do that 95% of the time, I'd recommend going to the gym 4-5 times like he's suggesting. Otherwise, stick w/ 3 times, or even less. I was 5'8" - 125 when I started. I was able to put on 40 lbs in my first year, and I didn't know ANYTHING about diet. I trained my whole body, taking every set to failure, 2x/week... and that seemed to work for me.
Make sure you train w/ high intensity... stick w/ big compound (multi-joint) movements as your base. Squats, deads, shoulder and bench press, dips/chins should be your base. I've been training for over 11 years, and these exercises still comprise the basis of my program. It KILLS me when I see small, skinny, or even normal guys at my gym doing endless sets of bicep curls and not training legs and back.
As Cure said, read on your own, come up w/ a program and ask more detailed questions. The guys on this board are great at answer great questions... not simple shiiite like... help me get huge... Lifting and being big, strong and lean is HARD WORK. If it was easy everyone would be jacked. You're gonna have to put the work in to educate yourself and ask the right questions before we can help you appropriately.
Good luck.