Replacing Bose headunit, can't get Sat Nav III voice!

[reserves]

New headunit is great but I have the Sat Nav in the DIS.

I can't get the sound to work as I don't know how to wire it up, I have the extra speaker in the door but i'm sure it used to go through the stereo first but still come out of this speaker?

Can anyone help or point me to somewhere I can work this out?

Also I have no AM reception, there was a big brown wire connected to the back of the concert head unit, any idea what this was because it already has an Earth?