Google it, but basically you turn the bike upside down, remove the caliper, remove the rebound knob, undo both nuts on the bottom of each leg then tap them with a rubber mallet and the fork legs will lift off.
Drain out the shite oil, replace the foam rings, if you think the seals are worn, replace them. Mine seem to last years without wearing as I service them often, so just do the foam rings. Basically you pull them out – its really simple and obvious. Replace with new ones soaked in the oil, refit the fork legs, refil with oil, redo the nuts, redo the caliper and your done.
TF Tuned do a kit that contains the oil, seals and foam rings.
Takes 15 mins to do, cost bugger all.