It's pretty straight forward - on the Seo when you pop the bonnet you'll see a couple of plastic brackets coming off the headlight, held in with a couple of 10mm bolts IIRC. Remove the obvious ones first and then just grab it and give it a firm wiggle, you should quickly be able to see what is holding it in. I also seem to remember that even when you remove all of the bolts, it still needs a bit of a gentle tug (tee hee) to work it free. Once it's free, just unscrew the old bulb holder and pop it in the back of the new headlight - refitting is the reverse of removal ;)