Navigate to the list of Content Types, choose Manage Fields for a type with CCK fields, then choose the Display Fields tab.

I'm trying to create a hidden field, so I select <Hidden> for the field label and then Save; the field and its label remain visible. I go back and select <Hidden> for Teaser and Full Node, and then Save; the field and its label remain visible. The only thing left to do is check the Exclude boxes. I read the instructions on Exclude:
"Use the 'Exclude' checkbox to exclude an item from the $content value passed to the node template."

My customers get angry when I write an instruction like this because it only makes sense to a programmer. What is "$content value"? If it doesn't get "passed to the node template", will the value not be saved with the form?

This instruction requires us to spend time learning the inner workings of Drupal before we can understand its message - even though, I suspect, it's trying to say something quite simple.