How to make blocks appear

Im trying to make traps and/or Dungeons in my game. but i don’t know how to make object appear behind the character, Please help.

why not have the character emit a block when he reaches a point in game

Player touches an object and the object emits another object. It’s called an emitter and you use it to spawn enemies or coins or whatever.

Thanx guys you helped a lot. Happy Hunting!