I'm a bit confused (Blame it on the Bulmers (other ciders available)).You have the Pc connected to the TV, but the sound comes out of the Denon/Wharfdales via the TV?
There should be some analogue inputs on the back of the Denon. They will say as such and be red and white plugs most likely. Take the output from your Pc (soundcard) either integrated or dedicated card, this should be a green 3.5mm jack socket. The 3.5mm jack plug to twin phono plug cable can then join the two components. If you have an optical output on the Pc and an optical input on the Denon, then you could use this method also.
You can connect your Pc to the Denon via a USB cable also, but the means to control music playback will be in your manual.