Before working on the phone, be sure that the device is turned off.
Begin by removing the back panel; this can be done by pressing the silver button on the backside of the Blackberry 8100, while simultaneously sliding the back panel off.
Using the spudger, pry off the back body panel by wedging the spudger in between the front and back panels on the side face. Remove the back body panel.
Some of these parts are fairly small and fragile; be sure to keep them in a safe place where they won't be damaged if you intend to reuse them.
Before repairing device, make sure to power off the device.
Once powered off, begin repair by removing the larger chrome ring holding the track ball in place by using the spudger to gently wedge the top ring away, approaching from the front face.