5-8 meals is for two things:
1) speeds up your metabolism
2) allows your body to completely process what you've eaten and pull out all the nutrients. If you eat one monster 2500c meal at one time, it will not be completely digested by the time it reaches your "end"...same if you eat more than about 40g protein (depending on how big you are - 40 is pretty high), you'll only digest a portion of that and the rest is wasted....you can't "pound" protein. Hence smaller (<40g) and more frequent meals. Each type of protein source digests at a different rate. I can't remember off the top of my head, but as far as I remember, beef is the longest at something like 6-8 hours, chicken is like 3-4 hours, whey protein isolate is like 30 minutes. So if you want to min/max, you could eat 40g of protein from beef ~8 hours before your next workout to ensure that you've got it's aminos floating in your blood.
If you are trying to gain mass w/o working out, stop. Like others have said -- you'll just end up getting fat.
If you're trying to gain mass while working out, then:
1) carbs are good but you have to balance it out based on your daily total calorie requirement...and not all carbs are equal: that is to say, sometimes you want simple carbs and sometimes you want complex -- depending on the situation. So drinking a sugary Coke CAN be a good things (eg. post workout w/ a bunch of fast-assimilating aminos).
2) raise your protein to about 1gm/lb body weight. If you're lifting (oops, I'm assuming weightlifting) HARD (meaning you're on the football team or lifting with experienced trainers), raise it as high as 2gm/lb.
3) keep fats to a min but you MUST get some fats. My favorite are peanut butter and flaxseed oil. So if you're eating meals with all carbs and proteins, you'll want to eat a tablespoon of peanut butter. And drink a tablespoon of flackseed each day (get the kind you have to refrigerate that has the sediments in it).
When you plan your meals, remember the protein requirements (1g/lb, up to, 2gm/lb), the fats (from #3 above), and the rest carbs. The harder ur workout, the higher the protein.
You can have complex carbs post workout (in fact you SHOULD - but with protein. This causes a spike in insulin and shuttles the proteins to your muscles - proteins need to be SIMPLE, so aminos are best or a simple protein drink (such as Syntrax - google it - "Nectar™ – Whey Protein Isolate" is like coolaid...easy to drink), simple protein so that they get into your system while you still have the extra insulin spike from the simple sugar -- DEXTROSE is best, but a bit harder to find).
The rest of the carbs should be mostly more complex: brown rice, fiberous potatoes (sweet, yams, etc), etc. Bread is pretty crappy. As is corn (too much sugar). Peppers (Bell, hot, whatever), onions, etc are great for adding flavor. Proteins should be stuff you make yourself and NOT sausage (it's too hard to tell how much of fats/carbs/proteins you're getting when it's all mixed up like that). Chicken, turkey, lean beef, salmon (has awesome fats), tuna, eggs (include the yolk fats in your math when calculating how much fat you are getting). Mix it up or else you'll get bored.
By all means, this is the tip of the iceberg. I'd skip most of the inet stuff and try to find a real live human whose done it already and work with them.
Good luck!!