Subwoofer X-Over and Speaker Hz Settings

I've read around on this subject and I'm thoroughly (easily) confused. I would appreciate some info on starting settings to experiment with.

I'm trying to choose the following settings: -

1) Crossover on the sub.

2) Hz settings in the receiver's speaker settings (separate settings for front and centre).

I have a 3.1 set up comprising: -

- Onkyo TX-NR-609 receiver

- Wharfdale 9.1 fronts (50Hz - 24Hz)

- Wharfdale 9.CS (70Hz - 24Hz)

- Wharfdale SW150

Used for music, movies and TV,all via HDMI.