l need to now how to get the tomtom to through the speakers

l do not think you can, unless there is a lead to fit to your stereo from the TOM TOM. The idea is that you fit it to your front screen and the glass reflects the sound and it can be adjusted to suit your taste using the volume adjustment within the TOM TOM.

there is plenty of volume through tomtoms own speaker, it can be adjusted too

Why? You can hear it fine enough just from the Tom Tom unit. Plus if you wire it into the car how will you remove it when you leave the car? You leave yourself open to having it nicked!