How to use a catch try catch?

My professor has given us a try catch block that he wants us to use for all of our code from now on for now. After reading up on it I am still a little bit confused on how to implement it into my programs.

The code he wants us to implement into our programs.

try {
return 0;
}
catch (exception& e) {
    cerr << "error: " << e.what() << '\n';
    keep_window_open();
    return 1;
}
catch (...) {
    cerr << "Oops: unknown exception!\n";
    keep_window_open();
    return 2;
}

One of the programs I am working on.

#include "std_lib_facilities_4a.h"
bool yes()
{
string y;
cin >> y;
if (y[0] == 'y' || y[0] == 'Y')
    {
    return true;
    }
else 
    return false;
}
int main()
{
enum {question1=1, question2=2, question3=4};
int result = 0;
cout << " Is what your thinking of red?\n";
if (yes() == true)
    {
    result += question1;
    }
cout << " Is what your thinking of round?\n";
if (yes() == true)
    {
    result += question2;
    }
cout << " Is what your thinking of an animal?\n";
if (yes() == true)
    {
    result += question3;
    }
vector<string> answer = {"You are thinking of a blue square!.","You are thinking of a red square!","you are thing of a blue circle!","You are thinking of a red circle!","you are thinking of a blue animal!","you are thinking of a red animal!","you are thinking of a blue round animal!","You are thinking of a red turtle!"};
cout << answer[result];
return 0;
}