usb communication with c++

Using Arduino Interfacing w/ Software on the Computer
3

ok..thanks for the help :)..i have tried the following..
configured baudrate in terminal by

stty -F /dev/ttyACM0 9600

then i created a c++ program(exp.cpp) in my computer

#include
#include
#include
using namespace std;
int main()
{
string str;
fstream f;
f.open("/dev/ttyACM0");
while(1)
{
while (f >> str)
{
cout << str;
}
}
return 0;
}

and uploaded this program into arduino uno

int led = 13;
void setup()
{
Serial.begin(9600);
pinMode(led, OUTPUT);
}

void loop()
{
digitalWrite(led, HIGH);
Serial.write("led");
delay(1000);
digitalWrite(led, LOW);
delay(1000);
}

finally compiled the exp.cpp and got nothing...please consider me as newbie to usb communication