There are two screws on the back, remove these first.
The back cover is snapped onto the front, at the top of the screen where the seem is, use a plastic tool (or flat head (plain) screw driver (be carefull not to mark the plastic)) slide it along the seem lifting the back cover slightly allowing the tabs to seperate. work from top and down the two sides. The back cover will then seperate from the front.
Colm, June 2010