A description of the dark secret is something very personal that a person has, it can be something very deep about your past that you have done.
It means not to try to shoot elaborate scenes, that sometimes the simplest things make the best photographs.
You can play this song in a simple C chord progression with C-G-A minor and F
1.) 3 situations for depth of field would be to a garden, a field or meadow, and a tree.
2.) same thing as number 1