Hey hopeful - first, have you done the first 3 steps with a sponsor? It's really important to take the steps in order - that's why they are laid out that way, and 4 is such an important one, when you are ready. The BB also lays out exactly how the inventories work - see pp65, and the entire chapter "How It Works" is critical.
That important idea aside - there are resources you can find online that have instructions - I used worksheets along the lines of these as I did my 4th with my sponsor -
https://step12.com/home.html