It's quite easy. The wiper blade is held in place with two small plastic tabs at the base of the wiper/wiper holder. Slide the wiper so it's in an easy to access position, then gently unhook the wiper off the two plastic tabs at the bottom to release, then pop the new one in place- making sure it's facing the same direction as the one you removed (note the lip on the top edge), straight and in all the way. DON'T touch the wiper blade with your bare hands/fingers, as oils from your skin can easily damage the print head.
I hope this helps.