Ok i will give it a go

Basic idea is to have the main speaker in the door where it should be, connected to the crossover.
The tweeter then needs to be roughly 30cm+ higher/away, also connected to the crossover.
The main speaker wire from the head unit will then need to be put into the crossover so that a signal is being passed through
Then you have a choice of either completly hiding the crossover or having it on show
Let me know what car it is going into and i will try and advise best placement