Problem with the pause function

I just started programming again and am starting over with C++. Now I just did an example I found and it is an if/else statement. At the end of the whole program right before the "return 0;" statement, I put the "system ("Pause");" statement. When I ran the example I was able to get to the prompt right before the if/else statement, but when I assigned the variable required for the program to return info to me, it just quit. I know the the "system ("Pause");" is supposed to keep the program open, but am I supposed to put this before I start my actual code or right under the "int main();" function?

This is the example.
========================================== /////////////////////////////////////////////////////////////
////////////If else statement by indigo0086////////
///////////////////////////////////////////////////////////
#include <iostream.h>
#include <stdlib.h>

int main()
{
int age; //Needs to be assigned a variable
cout<<"Please input your age: "; //prompts user for age
cin>>age; //the input is assigned to age
if (age<100) //If the age is less than 100...
{
cout<<"You are pretty young!"; //...displays this
}
else if (age==100) //if age is equal "==" to 100...
{
cout<<"You are old"; //displays this
}
system ("PAUSE"); //This is the line I am having trouble with
return 0;
}
==============================================
Now I can compile it but when I actually run the program it just opens and closes. But If take it out (the system function), when I put in my age to test it out, it quits. I am using Dev C++ and whenever you create a new document it adds this line above return 0; by default. I Is that is the right place to put it?