''Denny Crane! Master of the house.''
--'Chitty Chitty Bang Bang'Drivers on hills
Seriously, if you cannot move your car forward without rolling backwards you should not be driving. Nonetheless help is at hand!
Here is a guide courtesy of five spare minutes for those who’s memory has lapsed since they did their test.

This, is a handbrake. It is used to stop a car. If you utilise it then your car WON’T ROLL BACKWARDS INTO WHOEVER IS UNFORTUNATE ENOUGH TO BE NEAR YOU.
Steps:
1) Pull handbrake to apply.
2) Move forward and disengage handbrake.