One of the ways is to hit "like" on comments and posts that you think will do well. This is called "Curating", and you get paid if the content gets rated well by people with high "Steempower". Every 24 Hours you will get paid half in Steempower and half in Steem Dollars.
You can also deposit Bitcoin, Ether, and/or Bitshares to buy "Steem". Then you can hit "Sell/Buy", under your wallet, where you can sell your Steem for Steem Dollars.
Cheers
