Hi Jason,
The chord perfect changes are introduced in the first lesson of grade1.
edit:
the following is not relevant now this was split into its own topic
That is a better place to ask questions if you need.
To get there, You are likey to be starting at the community page, then navigate to the Beginner Grade 1 section, scroll down and select the “How to play the D chord” lesson and then ask your question in there.
Here is a link to the discussion so you don’t need to run thru all that stuff above. The perfect changes is introduced near the end of the lesson when you watch it.