How can I connect serial port with CGI?

For now I can get data from my webpage. So if I want to send the data to
serial port on mini2440 OS linux. 
Questions
1.Where should I start from?
2.On linux-example how can I run it from mini2440?

Thank you.

You should need to know about serial programming:
http://www.faqs.org/docs/Linux-HOWTO/Serial-Programming-HOWTO.html

Just write a C program (CGI) to read and write data.

Here is example:

#include <stdio.h>
#include <string.h>
#include <fcntl.h>  /* File control definitions */
#include <termios.h> /* POSIX terminal control definitions */
#include <sys/ioctl.h>

int open_port(char * serial_name);

/*
*   'open_port()' - Open serial port 1.
*   
*   Returns the file descriptor on success or -1 on error.
*   
*/
int open_port(char * serial_name)
{
  int fd;      /* File descriptor for the port */

  fd = open(serial_name, O_RDWR | O_NOCTTY | O_NDELAY);
  if (fd == -1)
  {                       /* Could not open the port */
    printf("open - ERROR \n");
  }
  return (fd);
}

int main(int argc,char* argv[])
{
     int ret;

     int mainfd=0;  /* Serial file descriptor */
  int nread, n_received;
  struct termios options;

  mainfd = open_port("/dev/ttySAC0");// com port 1
  if(mainfd < 0)
    return -1;
  
  
     
     /* Configure port reading */
  fcntl(mainfd, F_SETFL, FNDELAY);                  
  /* Get the current options for the port */
  tcgetattr(mainfd, &options);
  cfsetispeed(&options, B9600); // Set input the baud rates to 9600
  cfsetospeed(&options, B9600); // Set output the baud rates to 9600

  
  options.c_cflag |= (CLOCAL | CREAD); // Enable the receiver and set local
mode
  options.c_cflag &= ~PARENB;   // Mask the character size to 8 bits, no
parity
  options.c_cflag &= ~CSTOPB;
  options.c_cflag &= ~CSIZE;
  options.c_cflag |=  CS8;      // Select 8 data bits
  options.c_cflag &= ~CRTSCTS;  // Disable hardware flow control

  
  options.c_lflag &= ~(ICANON | ECHO | ISIG);  // Enable data to be
processed as raw input

  /* Set the new options for the port */
  tcsetattr(mainfd, TCSANOW, &options);
     //write(mainfd, "test_", 8); // test 

     
     /* Close the serial port */
     close(mainfd);
     return 0;
}