What a f*cking mess! Tommk3cab hit the nail on the head when he said some people shouldn't bother when they clearly don't know what they're doing...
I don't think you need me to tell you that lot is butchered (my favourite bit is the wire that has been lengthened by all of 4cm's with a piece of chop-block - quality

)
So, getting down to business, putting that mess straight;
Do you have (and can you use) a multimeter? We need to identify what each one of those nasty little scraps of wire are, and connect them into the ISO block, which will allow your nice new shiney head unit to be plugged straight in with zero fuss.
If you don't have (or don't want to buy) a multimeter, then I really think your best bet would be to go a local car audio shop and have them straighten it out for you - you're really only looking at an hours work (max) for someone that knows what they're doing, so it'll cost you no more than £40
If you have a multimeter (or are prepared to buy one) but don't know how to use it, I can type out some fairly simple instructions that will show you how to use the multimeter to identify what is what and connect it all up. Once you've learnt how to do it, it's very easy and will save you loads of hassle in the future (plus it will allow you to help friends etc out when they have the same issues).