Unable to satisfy contraints on package httpd

I'm following pluralsights "Getting Productive with Chef Cookbooks". I tried the courses at learn.chef.io but I wasn't able to understand chef with them.

Running berks install after setting up a metadata.rb file I'm getting:
"Unable to satisfy constraints on package httpd~> 0.3.3, which does not exist, due to solution constraint (webapp-linux = 0.1.0). Solution constraints that may result in a contraint on httpd~> 0.3.3:[(webapp-linux = 0.1.0) ->(httpd~> 0.3.3 >= 0.0.0)]
Missing artifacts: httpd~> 0.3.3
Demand that cannot be met: (webapp-linux = 0.1.0)
Unable to find a solution for demands: webapp-linux(0.1.0)

Can someone tell me what any of this means? What constraints? Why does my custom cookbook rely on httpd? webapp-linux is my own cookbook I'm writing/copying for the course.

Hi there! I reached out to the author of that course, and he indicated that the particular course is a bit old now. He's recently published new Chef courses on both Windows and Linux, which you can find here: https://www.pluralsight.com/courses/developing-local-chef-cookbooks-linux

He also offers support via Pluralsight and GitHub, so I definitely recommend reaching out there for more specific assistance!