The headlight should be fairly easy Dae, theyre typically a screw in screw out component that holds the light which mounts into the back of the light fixture. When you pull it out, do so slowly so you can see if there are any bayonets on it and whether they have a high/low level so you put the new one in the same way.
I had a similar issue with one of my rear lights, put the globe in back to front (some how) and it was dimming on hard brake instead of getting the second stage of brightness, and was over bright normally.