Help installing a head unit into an 07 impreza pleasee?

Big mistake. You should have got an adapter harness. Anyway, it looks like you have the right diagram. You need to check that you're actually getting power to the unit. If the car has an external amp, that's probably where the problem is. You may need an amp eliminator or adapter harness for that. The remote wire is to turn on an amp or something like that. It can not be used to power anything.