Here is a fun, brief introduction to cell signaling. I think it’ll be worth your 9 minutes to watch this as it shows nicely how things fit together before you get into more detail with some of the material in the chapter.
Here is my lecture on cell communication (Chapter 11). This chapter, more than most, follows the textbook very closely, so it may be best to work through this in parallel with the textbook.
I also encourage you to read this OpenStax chapter. It contains much of the same material at about the same level as we cover. If you find some aspects of Campbell confusing, you might do well with a slightly different perspective offered there.