How to use your reader's imagination . Read the page I have on this. How to show and not tell. This is part of learning how to make the reader work, and is also a somewhat difficult task. It is too easy for an author to patronise the reader by telling them what is going on, or what a character is like, rather than showing them.
Actions are more important than words.
He was a bigoted, hot-tempered idiot. Instead, show the reader why kind of guy John is by using his behaviour to make the reader realise the guy's not very likeable. How to present background information. That is also patronising the reader. We can learn gradually as the story unfolds of the long and torrid history of the relationship between King Fred and Wizard Emily.