Unplug or trip the breaker to the unit.
This is very important because on many units one side of the element is still live even when it is off.

Remove the screw/s that hold the element to the back of the oven.
Gently pull the element into the oven.
Disconnect the wires from the element.
It is a good idea to clip something (clothespin etc.) onto the wires so that they do not disappear into the back of the unit before you get the new element installed.
Check that the old and replacement element are exactly the same. A critical measurement is from the mount to the end of the element. If it is too long the element will short to the back of the stove.
Check the connectors for pits etc., clean them if necessary.
Install the element in the reverse order.