I've just made a few changes.

Code:
#include <iostream.h> 

const int minute = 60; 

int main () 
{ 
//Announce purpose of program: 
cout <<"This program converts seconds to minutes and seconds."<<endl; 

//User inputs seconds to be converted: 
int seconds; // to be input from user 
cout <<"enter seconds: "; 
cin >> seconds; 

//Check error state 
if (!seconds) 
{ 
cout <<"You must enter intergers only." << endl; 
return 1; 
} // if 

//Convert seconds to minutes and seconds in integers: 
int second = seconds % minute ;
int minutes = seconds/minute;

//Display the results: 
cout <<  seconds << " seconds is equivalent to " <<  minutes << " minutes and " << second << " seconds." << endl; 

return 0; 
} // function mainin
} // function main