Reach Chapter 6 entirely, and Chapter 7 but stopping at the "Project 6" section. Chapter 6 is about analog reads and writes, and covers much of what we've done, but explains it in dramatically more detail and in a more organized way. You can ignore the material on analogReference. The content on map and constrain is possibly a little confusing, but worth taking a look at.

Chapter 7 up until the Project 6 section focuses on some content you know, like delay, and also some other material, like random numbers.

As usual, find the reading forum and post a question or comment.