Step 1: Embed your quiz on yoursite.com/quiz
Give that page an H1 title that is the title of the quiz but abbreviated, focusing on the top keywords associated with your quiz.
Step 2: Above or below your quiz add content sections
About the (Quiz name) quiz: Write some content telling people about the quiz and why it's beneficial to them.
How to take the (Quiz name) quiz. Write some content telling people how they should take the quiz, what mindset to have when taking it.
Why I created this (Quiz name) quiz. Write some content telling people why you created the quiz and what its purpose is.
(Quiz name) Instructions. Write some content giving instructions on the quiz, and what you envision for people taking the quiz.
Overall you want 200-300 words, and here's an example of what it can look like when the content is above the quiz. You can put it above or below the quiz embed.
Step 3: Make sure your quiz is optimized for all devices
Make sure that after you add the text sections to the quiz page you can still take the quiz easily on all devices.