If you're not sure about what you're doing, then I would highly recommend having a professional do it...
but you'll basically end up taking everything apart...I did it about two years ago but so I can't really remember what I did exactly...take off everything on the front of the cluster, i think the bezel should be the last piece, then you should just have the seperate gauges. there should be 2 or 4 screws behind the fuel/temp gauge, so you unscrew that and the gauge should just come out...then just piece everything back..like i said, I dont really remember what i did so be very careful and if you're unsure, have a pro do it.