C reference manual

Not sure what you're seeking here:

Do you want to learn the 'C' programming language?
If so, any standard textbook will do for that:
blog.antronics.co.uk/.../

Do you want to know the specific implementation details of Keil's tools?
If so, the Keil Manuals are what you need:
http://www.keil.com/support/man_arm.htm

Do you want to know specific details of the STM32 chip?
If so, the Manufacturer's Documentation is what you need:
http://www.st.com/stm32

Not sure what you're seeking here:

Do you want to learn the 'C' programming language?
If so, any standard textbook will do for that:
blog.antronics.co.uk/.../

Do you want to know the specific implementation details of Keil's tools?
If so, the Keil Manuals are what you need:
http://www.keil.com/support/man_arm.htm

Do you want to know specific details of the STM32 chip?
If so, the Manufacturer's Documentation is what you need:
http://www.st.com/stm32

Wait a minute!

I am new in the arm enviroment and i want to learn about these, so i bought a cheap chinese board with a st32 arm cortex m3 inside.

#include <LPC21xx.H>                       /* LPC21xx definitions */

void wait (void)  {                        /* wait function */
  int  d;

  for (d = 0; d < 1000000; d++);           /* only to delay for LED flashes */
}