Page 1 of Dolby 5.1?

I know I`m thick but just to prove it, if my DVD player has a built in decoder do I need to connect it up to an amp of some descriptiojn or can I just connect speakers up to the right sockets on the back?

you need a suitable amp which will accept the inputs from your dvd.

This is because the dvd player does not have amplification built in. You will either need a amp and speakers, or you could buy something like the Bush 300 or Novatech (www.novatech.co.uk), which are a cheap "all in one" package - 5 satellites, sub and amp for all channels built in to the sub. These will be around £100. They won`t sound the bees knees, but might be enough to get you going, and if you choose to upgrade, you haven`t lost much. Have a look at this thread http://www.dvd.reviewer.co.uk/forums/thread.asp?Forum=211&Thread=60831 - I posted a link to several threads on this subject.
Next step up is something like the much mentioned Yamaha VS10 (£300), which has a separate amp and sub & satellite speakers. Comes with all cables, and will also do the decoding for you (although you have that facility on your DVD player).