I am trying to make a script that allows the camera to move forward and backwards only when u put two fingers on the touchscreen and if you slide the fingers forward the camera will go forward and if you slide them backwards the camera will go back within a certain limit. How should i do this? (I am developing for iphone)
I would look at the Input.Touch interface in the Script references.
There are some examples showing how to use them.
Once you understand how Input.GetTouch works, you should be able to translate the deltatouch values into camera translations.