This guide for standard halogen bulbs only. If you have xenon lights then it may differ although taking the light units out should be the same. It's easier than it looks to do. One you have the trim under the headlight out it's actually quite easy!
1. Open the bonnet. See Opening and closing the bonnet.
2. Remove the screw.
3. Using a suitable implement, remove the trim panel. It's only a push fit and you can prise it off carefully.
4. Release the retaining clips. (squeeze together)
5. Disconnect the electrical connector.
6. Disconnect the headlamp washer hose (if you have one).
7. Remove the headlamp.
Note: When fitting the headlamp, make sure that you fully engage the headlamp in the retaining clips.