The Health & Safety Police do not want you to be doing this - the bulb is inside and to get to it you will need to take the cover off - the user guide does not give any advice about doing that.
Dangerous radiation and very high voltages lurk inside - even when unplugged the capacitor can give a nasty shock.
The expectation is that you will get a trained specialist to do the work - if you decide to do it yourself you will need security driver bits.
Stay safe...
October 2015