I am currently 6'4" and I only weigh around 130lbs - 140lbs. I have a problem with eating. I can only eat very small portions at a time getting full extremely quick and I refuse to eat red meats. Also I have a very fast metabolism along with that. So, I was wondering is there any easy way to gain weight. My ideal weight would be like 185 - 200.
Hey I'm guessing you're a guy -- how old are you? Why do you want to put on weight (e.g. health or just lookin good?)?
Odds are, with a fast metabolism (and if you are a teenager or early 20s) your body simply isn't getting the protein it needs. I suggest a protein shake for breakfast (morning is a good time to ingest protein). Whey protein is considered "complete" in the sense that it contains all the proteins your body needs to synthesize muscle tissue -- some protein (steak, e.g.) doesn't contain all the proteins and must be consumed with a complementary protein for maximum benefit.
Your body will grow muscle just in the course of your normal day, and if you are already exercising regularly (playing sports, running, whatever) you will probably add mass and tone simultaneously.
If you're really interested in it, I suggest Arnold Schwarzzenger's Encyclopedia of Bodybuilding. While its aimed at bodybuilding (which is probably not what you want to do), there is also lots of information about diet and exercise which can apply to any person looking to stay lean and fit. The pictures also give you a good image of how muscles develop, which is useful in gauging your own progress and adjusting your routine to stay balanced.
If you're really
really interested, consult a dietician.
Edit: I read the whole thread. I was really skinny as a teenager, started working out in college and got a bit bigger. Instead of focusing on eating a lot, focus on diet and fitness. If you exercise enough, your body will demand more calories to keep up. Consume these calories as complete proteins and you will grow muscle. To some degree, it also takes time. Your body is so busy growing up that it doesnt have the time or energy to grow out. As you move through your development your body will begin to fill out naturally. If you're busy exercising then you will fill out with muscle tone...otherwise you'll fill out with fat.