i need help creating a if then program

First if you have a #include with nothing after it the program shouldnt be able to compile
and if you just want to wait for the light you can remove the if(analog10(0) > 30); as how you wrote it it wont do anything and wait_for_light will already wait for the light to be turned on after calibration is complete. I may be wrong but I do not believe that you have to do enable_motors. Also at the end you need to sleep to allow the motors to finish moving you do this with bmd(motor). The final thing though is more of a personal choice and that is to use mrp instead of mtp. Here is the code I would use instead:

//define the light sensor so its a little more readable
#define LIGHT 0

using namespace std;

int main()
{
wait_for_light(LIGHT);
mrp(0,500, 1000);
mrp(3,500, 1000);
bmd(0);
bmd(3);
}

This will wait for the light then move forward 1000 ticks at 500 ticks a second(unless i got the last two arguments backwards)

The reason the include wasn't showing up was because of html weirdness. I went ahead and encapsulated your code in <c> blocks to prevent that from happening.

I think the error is caused by the lack of definition of the  enable_motors(0, 3); function.

ruler501 is correct about the if not functioning as expected. Remember that an if is executed only once. It does not wait for a condition to be true to continue.

I would recommend using a while loop to wait for a condition to be true. You can find examples in KISS's built in documentation.
Or, if this is a competition robot, it is strongly recommended you use the wait_for_light(int port); function. This allows you to calibrate your robot for the possibly stronger or weaker lighting at the tournament.

Good Luck!

thanks every thing now works great.