How do you place blocks outside of the stadium?

Hi,
I would like to know how to place blocks out of bounds. When I try to do this with challange edit, the block simply disappears.
What am I doing wrong?
Sincerely,
CX
EDIT: Also, I want to apply a mod, holding control while opening it only gives me the option sunrise, day, sunrise and night..
I would like to know how to place blocks out of bounds. When I try to do this with challange edit, the block simply disappears.

What am I doing wrong?
Sincerely,
CX
EDIT: Also, I want to apply a mod, holding control while opening it only gives me the option sunrise, day, sunrise and night..