simple RC car servo steering...

Hi

I have been trying for days to get some basic servo steering for toy rc car I removed the old custom 6 pin servo and replaced it with a normal 3 pin servo.

But I cant seem to get the servo to centre again when left/right button is not pushed down.

I have looked for some tutorials abut they just seem to be for servo sweeping. So far I can make it pan left or right then pan back to centre but not stay left or right with button pushed down. Plus I think there must be an easy way to do this not with modified sweep code.

for code I used http://blog.richard-potter.co.uk/2009/11/servo-control-with-an-arduino-board/ but I really cant seem to work out what to do... i have used so much different code from examples to my own guess work and none works how I would like it.

I would love any help or pointers where I should start Thank you