There are many ways.
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, and check out my video: https://steemit.com/ethereum/@crypt0/ethereum-news-what-is-steem-should-you-invest-some-ether-to-avoid-hard-fork-losses
for more info. Please hit like and share the love. Just did the same for you :)
"Every 24 Hours you will get paid half in Steempower and half in Steem Dollars." I have made a number of posts, that show dollar amounts next to them, but my wallet only ever shows me having .001 steem dollar? My steam power shows (+4.5) is that somehow convertible to steem dollars? Is there as setting you can change as to how you are paid (dollar or power). Perhaps I inadvertently changed it.
So ultamitlly you have to pay into to buy Steem dollars that, makes no... since I thought ultimately people vote for your photos and you make steem dollars that way,.. not hat you have to Buy into anything,... :-/