Flowcharts
The flowcharts in this book will follow a similar style to those shown in the flowcharts section of the Programming Fundamentals textbook (by Busbee and Braunschweig) , which is available for free from libretexts.org. I'll include examples as each symbol is introduced in this chapter, but I still recommend reading the flowcharts section of the book linked above.
Software
If you want to edit flowcharts collaboratively or want a convenient web app to work with, then I recommend app.diagrams.net. There are also free programs that specialize in editing flowcharts and other diagrams. The examples you see in my notes were made using Dia.