New headunit, power but no sound

[Scots]

I know this has been covered quite a lot. but I’m getting power to the nee headunit, but I’m not getting any sound. I’ve been told it’s because I need to get send a signal from the blue and white wire on my nee headunit to a wire on the cars audio harness, but I can’t seem to find the right connection to get the factory amp to turn on from the new headunit, I’ve blown two fuses trying to find the correct one.

 

so I’ve taken some photos of the factory plugs and I’m hoping someone can tell me what one I need to connect it to. 
 

any help would be very appreciated 

 

thanks