You can earn Steem or SBD by creating content that other people upvote. This can be things like:
- Blog posts on Steemit.com or Busy.org.
- Photos on Steepshot.
- Questions or answers here on Musing.
- Videos on DTube.
- Finding products on Steemhunt.
There's also more options, as well as curation income, which you will get when you vote for something.