Eat, eat and then eat some more. If you want to be big you must eat big. And I'm not talking about eating out your girl I'm talking about proper meals. Well balanced with plenty of protein and carbohydrates, avoid saturated fats.
Make sure that your protein sources are high quality (the amino acid profile must be high). Here is a protein quality chart:
http://www.bodybuilding.com/fun/planetfig3big.jpg
The following links are very useful:
http://www.bodybuilding.com/fun/planet4.htm
http://results-sports.com/articlespage.htm
Make sure to get plenty of rest, a minimum of 8 hours sleep every night. Drink water like you have been stuck in the Sahara Desert for days - it is the most anabolic substance on earth. The following article details how much water you should be drinking per day:
http://results-sports.com/article5.htm
Make sure you use "the window of opportunity" that is the post workout period. This is the time when your body is primed for nutrient intake and start the rebuilding process. I recommend taking whey protein as it is the fastest absorbed protein known to man and has a high protein quality. It is also very convenient, although most other high protein quality protein sources will suffice. I just find whey to be very convenient and it is cheaper than real food if you get it from the right places. You must also replenish your glycogen stores. Do this by consuming a high GI food. Check out the following link if you are not familiar with the Glycemic Index:
http://www.glycemicindex.com/
My personal choice for the high GI food is glucose, dextrose is another name for this substance. It is pure sugar and has the highest GI of any carbohydrate. Maltodextrin is a suitable alternative.
You must lift heavy, I recommend lifting in the 6-10 rep range. One of the principals of hypertrophy (The enlargement of a body part due to an increase in the size of its cells). Is use or it or lose it. Basically if your muscles haven't been challenged for a while your muscles will atrophy (get smaller) and you will lose size.
Don't go crazy on cardio, it will burn precious calories and / or muscle. I think a maximum of three sessions should be performed, I recommend performing at least one for general fitness and well being. Keep the cardio intense, my personal favourite being HIIT. See this link:
http://www.affordablesupplements.co.uk/ns/products/article.asp?articleID=25
The exercises I believe are essential for optimum muscle growth are, in order of significance:
Back Squats, Deadlifts, Bench Press, Barbell Rows, Overhead Press and Pull Ups.
As far as supplements go, as mentioned previously Whey Protein and Glucose are good for Post Workout Nutrition. Creatine has been proven to help increase muscle size, strength and endurance. But I don't recommend it unless your diet, training and lifestyle have been optimised.
Also, I do not recommend smoking weed or drinking as both suppress testosterone which is an essential hormone for muscle growth.
Make sure you read the Calorific Efficiency articles from Results Sports as they are very useful. If you have any questions I would be happy to help out.
Good luck