Banking

So I keep asking smart people why we don't just print more money. I mean we make money right? So why don't we just make some more? Well for a wile everyone just told me that it would lower the value, and I understand that but I still didn't REALY get it. I mean I've heared it explaind sooo meny diff. ways by sooo meny diff. people and honestly I DO get it. I geuss it just seemed pointless somehow, but then I asked Uncle Andy and he explaind that we get our money from this huge bank made out of a bunch of small ones. He said that even though the bank was part of America they didn't REALY answer to us and we already owe them alot of money. Now I don't know how much of this is accurate but it makes sence to me.