Lie the pedal flat on the floor (a carpeted surface, ideally), find the correct open-ended spanner to secure the flatted end of the axle (where the pedal normally screws onto your crank)
Now find the correct socket to loosen the locknut inside the pedal body - stand on the spanner to hold the axle in place, then loosen the locknut with the socket/ratchet. (anti-clockwise if I remember rightly) I usually use a small flat screwdriver to remove the lockwasher and cone. Just use the driver to hold the cone in place and turn the axle by hand to remove it...
