You could first start with the website itself here and the pages at the top: https://steem.io, however be aware that the Whitepaper is quite outdated.

You'll also find this helpful: https://www.steemithelp.net

The best way to learn is also by doing, go get curating and commenting as well as posting the very best content you can as regularly as you can.

Don't get overwhelmed too soon, think in the long term. Hope this helps.