The cliff notes version is that because the community has it's own cryptocurrency, the money is distributed through upvoting and discovering new content. It can be difficult to wrap your head around, I'm new as well. I really recommend just reading content and maybe checking out some Youtube videos on how Steemit works before. The FAQ is handy: https://steemit.com/faq.html It still took me a while to really work it out even with the FAQ though, I watched quite a few Youtube vids. This one explains the currency really well:
This one is good for explaining the currency: