You need to register it with your town hall (for road tax) and get it to an ITV testing station - not sure in what order. You need to send part of your UK reg doc back to DVLA; if you've only just become resident, and you've owned the car for more than 6 months, you should be able to avoid paying matric. tax, but you may need a letter from the British consulate; you may need to take large quantities of valium.
TechNoApe brought his car from the UK recently and was going to re-register it and write a book about his experiences later, but having heard no more about it, I suspect he's somewhere in a soft room quietly banging his head against the walls.
I actually went through the process about 12 years ago, but paid a gestor to handle all the paperwork. I still had to take the car to be "homologated" although it was a relatively painless process from what I can remember - I was still suffering culture shock at the time.
I suggest you contact a local gestor for assistance.