Easy job.
You probably don't even need to replace them - you can clean them with a thin bit of stiff plastic - an off-cut from a film negative is ideal, push it under the seal and move round to pull out any crap.
Even if you do need to replace it's not difficult - Remove front wheel and axle, and mudguard etc. Loosen, but not too far (just crack it loose) the 6mm bolt holding the damper rod at the bottom of the fork, and remove the fork cap with a 24mm socket/wrench (careful, soft threads and a spring underneath) and remove the spring. Remove the fork from the bike (10mm socket for the triple clamps, 10mm allen and 12mm socket for the axle, 4mm allen and 8mm socket for the mudguard, 8mm?? allen for the callipers), and pour out the fork oil (you'll probably want new stuff). Remove the 6mm allen head bolt in the bottom on the fork to release the damper rod. Prise the dust seal up with a screwdriver or similar under the seal lip (carefully), unhook the retainer ring with a small screwdriver, and then 'slid hammer' the oil seal and bushing out. Reassemble the fork, replace the 6mm damper rod bolt, and you can drive the bushing back in with the large washer. Drive the new oil seal in with a seal installer (I have one you can borrow), reinstall the retaining clip, and push the (new?) dust seal back in. Refill the fork with oil, reinstall the spring and refit the top cap. Reinstall the fork leg onto the bike.
It sounds bad, but it's not difficult. I have a fork seal driver you can borrow if needed. The stumbling point is right at the beginning - removing the mudguard is the worst bit imo.
