Hello Kal,
Undo any screws holding the front of the door seal onto the front of the machine, you may find a very large circular holding clip round the front of the door seal instead, once you have taken that off prise the rubber away from the front of the machine, you can now see where the door seal is fitted onto the main drum, look for any retaining spring and take it off, fit new door seal reverse way of these directions, make sure the holes in the door seal are at the bottom, if it is tight fitting put some washing up liquid round the edge so you can push it on easily.
DO NOT GO INTO THE MACHINE UNDER ANY CIRCUMSTANCES UNLESS THE PLUG IS OUT AND BE AWARE OF RAZOR SHARP EDGES ON THE MACHINE.
Ken
drivewithken@blueyonder.co.uk, July 2007