Gaining 6 pounds in 2 weeks as a beginner sounds very possible, but if you are already seeing your midsection gaining fat, you should cut back on your calorie intake some. In having a healthy lifestyle, all sources of nutrients are necessary. There is a time for all kinds, protein, complex carbs, simple carbs, fiberous veggies, and even saturated/unsaturated fats. The trick is to learn when it's best to eat what. before and after your workout, you want a good amount of proteins and complex carbs. Directly after your workout (within like 20 minutes) you want proteins and simple carbs (to boost your glycogen levels back up to normal). Consistantly eating veggies and fruits throughout the day is just healthy in general.
Now, granted, that's not even close to covering everything related to what you are talking about, but those are just a couple of general rules that you need to learn. The average amount of weight gain (during SERIOUS bulking cycles) is still only 1-2 pounds a week. After that, it's mostly fat and water retention.