Steemit allows you to do the things you're already doing on other social media sites but you get a financial incentive to put out good content.

Instead of getting meaningless "likes", upvotes have an actual monetary value that you can cash out once your post is 7 days old.

Now for the confusing part:

• Steem
  • Steem is the main currency of the steem blockchain. It is traded on exchanges so its value fluctuates constantly. You can cash this out at any time.
• SBD
  • SBD (Steem Based Dollars) is a secondary currency, it's usually worth around 1$ of Steem.
• Steem Power
  • Steem Power is essentially Steem that you lock up to power up your upvotes and increase their value. You can "power down" at any time and wait 30 days to get it back into Steem.
• Voting Power
  • This is your energy bar. The lower it goes, the less your upvotes are worth. This is true even if you have a lot of Steem Power. Every time you upvote a post or a comment your voting power goes down a bit. This refills at the same rate for everyone.
• Steemit
  • Steemit.com is one of the front end for browsing content on the steem blockchain. (It is similar to reddit in design.)

I hope that helped someone!

Much love <3
@Chiren