"I want to know how Justin Sun bought Steemit, and how he controls and censors the press and public opinion. Did Justin Sun give money to Steemit users and buy Steemit?"

Justin Sun purchased the STEEM stake of SteemIt, Inc., the company which owned by far the largest single stake on the Steem blockchain. With it, he had the voting power to put his own Witnesses in control of it. Far more to the story than this, but ... This was the starting point.

"I don't know the relationship between Steemit and Hive."

The "old guard" Witnesses of the Steem blockchain, led by BlockTrades, decided they would simply start their own blockchain, instead of continuing their "war" with Justin Sun.

• Note: In this "war," a number of prominent Korean stakeholders attempted to "control" the outcome. They failed. As a consequence, they were not allowed to participate in the initial Hive token airdrop. So ... As far as I know (I am no longer participating there ...), they are still active on the Steem blockchain, making who knows what "deal" with Justin Sun ...

"I've seen you write about how you can earn money by moving Steemit's tokens to Hive."

I powered down almost all (I have a tiny bit left there, to support commenting ...) of my STEEM stake. In the volatility of the markets, in exchanging STEEM for HIVE, one can either make some money or lose money. I did okay ...

"Have you written how to invest in stocks?"

Nope.

Hope this helps you!