It falls on this 3 categories:
1. More buyers means more demand = the price goes up
2. More sellers, less buyers = the price goes down
3. Less buyers, means less demand = the price goes down
So basically that's how the market works, so its law of supply and demand. Go and look for basic law of economics and try to understand it. I'm in the same boat with you man, I didn't quite understand at the beginning. But through constant reading and going around the forum, I was pointed to the right direction.