ArmA 3 Editor Tutorial - Clear the Area Mission

Hi there! Today i showed you guys how you can create a mission, clearing the area with trigger codes.
CODES:
(!alive enemy1) AND (!alive enemy2) [You have to type this codes on trigger condition.]

[@happydome8304]

Hello this is a good video, but I'm trying to do this exact same thing but for searching a locker full of items. How can i make it so when the player searches the locker, the task is completed?
Also, is there a way to make the task marker visible on screen?