How to enable a trigger box with another trigger box?

I am trying to cause a trigger box to enable another trigger box, but can’t figure out how. I found another topic on this forum with an answer, but unfortunately the images no longer work, and the answer isn’t explained clearly in text. If someone was able to explain what was being done in this answer I’m sure it would resolve my problem.

Here is the topic I’m referring to: Is it possible to enable a trigger box with another trigger box?

This is one way