baby steps you will get there just need to try and break it down into it's basic elements.
I would say it's like digg meets blockchain.
You will need to know your audience as most people probably barely know anything about bitcoin on a technical level.
In the old days people would have their name written in a book and to change ownership the name would be crossed out. This is just a secure and more distributed version with each book keeper checking each other.
Then maybe move onto publishing and creation how that works traditionally and draw as non technical comparisons as you can.
a lot of people watch TV, Twitter or Facebook. How does steemit compare to these systems? Art industry or Music industry how does talent get discovered what's a curator? this kinda thing.