Add digital aerial to new radio

I cannot but congratulate the Halfords lad that took out my old radio and replaced it with a new one. This was an easy replacement as all the plugs and VHF aerial interfaced easily but it was new territory to me. This radio also has a Digital capability, so the lade sold me an aerial that sticks to the corner of the windscreen. Easy to get the wire down to the dash board but how to get it through to the radio? Do I need to take the dashboard out?
While I'm at it I would like to add a supply up there for a camera. Can someone help me here?