The first thing to do is to turn your light switch off
If you have to reach above to remove and bulb then make sure you have a safe ladder and it is on an even surface.
There are usually two types of bulbs.. a bayonet and screw in type.
Make sure the bulb is cool to the touch. If not use a cloth to hold the bulb then push it in and twist anti-clockwise. (This will release the pins from the lamp holder) then pull down to remove.
Push the bulb into the bulb holder making sure to line up the pins on the bulb to the socket on the bulb holder. Twist clockwise to lock into place
Screw in Fitting
Twist anti clockwise and remove from the bulb holder
Twist clockwise until you can’t turn it anymore
Once the lamp is secure turn on the power and switch on the light switch to test.