Deltatime is a constant... just reference it in your event by using Background.x=Background.x+6*dt (experiment here...)
Actually delta-time is not constant, it is time that has been elapsed since last tick occurred. That can vary. :)
When using delta-time, you really can't say 'move 6 pixels forward every tick' as you are just going against the whole principle of the thing. Instead, you can say that 'move 6 pixels in time frame of one second'.
DT creates framerate independence. Regardless of what FPS player has, the object will move those 6 pixels in time frame of one second if you are using dt. If you are not using it, player with lower FPS would move LESS than player with higher FPS, as he will have less ticks in a second.