When the cover is off you can access the sim card, memory card and battery. Be careful when removing the cover because, like me, if you are a bit rough with your handling you can cause a creaking sound to develop when pressing against the cover whilst using the qwerty keyboard.
Here is the proper method on how to remove the back cover:
1. In one hand hold the device so that the camera button on the side of the device is facing upwards
2. With your other hand put a nail in to the groove that is 1cm away from the camera button
3. Pull the cover away from the phone and it will "snap" away - use a little gentle force
When putting the cover back on, put the USB port part of the cover back on first, then snap the rest of the cover on.