Can Someone Simply Explain Steemit to Me?

I recently just got a steemit account and I am so lost. I've done some research and am still confused. I can kinda understand how to earn steem or steem power and everything but I'm really confused on what I can do with them. What is powering down your steem power and should I constantly convert my steem to steem power? Or should I just leave it? What is the savings for and what should I be transferring to the account?

I am so lost right now. If there is anything I should know feel free to comment. I appreciate all your answers. Thank youuuuu :)