Mining STEEM

Hi Guys,

I've got a question concerning how STEEM works. I've read the whitepapers and stuff, but there is so much I have some troubles following that.
2 Years ago, It was possible to mine STEEM in an experimental proof of work : https://bitcointalk.org/index.php?topic=1410943.0
And miners could earned SP.

Then, now It seems It's not possible anymore :
https://steemit.com/faq.html#Can_I_mine_STEEM

So who mine the STEEM blockchain now ? How does it work and what are the rewards?

Because I wanna make a local fork on the steem blockchain & mine it in its current to see how it works :)

(Another question comes out : Do I need a license to fork steemit ? or can anyone fork it and use it?)

Thanks guys !
Arkinex