The first piece of advice for replacing for seals would be to always get a workshop manual of some description when stripping major components down, if only for the torque settings.
But it's a pretty straight forward job.
Undo the allen bolts at the bottom of each fork bottom (inside the spindle hole). Drain the oil out, undo the fork top nut (not the preload adjuster) and the whole fork damper cartridge and spring will come out as one piece.
Lift the dust seal at the top of each fork bottom and slide off. Underneath you will find a wire type snap-ring which holds the oil seal in place, remove them.
Then using the fork bottom and stanchion as a slide hammer gently knock and pull them apart bit by bit.
Remove the old seals, then clean the stanchions and check for pitting or wear. Put some of the same fork oil you are using on the new oil seals to help them slide down the stanchion.
If you haven't got a seal fitting tool, then put the old seals back on, on top of the new seal and use them to drift the new seal into position gently. Make sure the top fork bush is seated before doing this! Replace the snap-clip in its groove and the dust seal.
Then refit the fork cartridge and bolt it back in, pull the stanchion down away from the top fork nut, then add the correct amount of oil.
If you put a rag on the top of the top fork nut you should be able to pump the cartridge on the spring to bleed the damper before refitting the top nut