You need to check that you are getting fuel and spark. To check for spark pull a plug wire loose from a spark plug, stick a screwdriver inside the boot, and hold it about a quarter inch away from a ground. Make sure your hand is not near the metal part of the screwdriver. Have someone turn the car over, and look for spark. To check for fuel what I usually do is take the line loose somewhere and put in a bottle and turn the key on for bit, look and see if any gas poured in. Some cars have valves you can press a key down on a stem and gas will spray out.