how does this site work ????

Well described

You need help with what ... Need more information to help

Here's a great post explaining how to use Steemit:

https://steemit.com/help/@lehard/steemit-for-dummies-guide-for-newbies-en-ru-fr-nl

Here's a post I wrote explaining what Steem, Steemit and cryptocurrency is:

https://steemit.com/steemit/@thewisesloth/introduction-to-cryptocurrency-and-steemit