C++ help: loops and switches

How do I go about looping options 1 and 2 considering it's a switch? New to programming and having difficulties solving this. Any help would be m uch appreciated!

#include <iostream>
using namespace std;

int main()
{
    int userOption;

    cout << "Hello user, what would you like to do?" << endl;
    cout << "Option 1: Display a message" << endl;
    cout << "Option 2: Perform a calculation" << endl;
    cout << "Option 3: Exit program" << endl;
    cin >> userOption;

        switch (userOption)
        {
            char op;
            int num1, num2;

        case 1:
            cout << "Welcome user!" << endl;
            break;
        case 2:
            cout << "Enter + for addition, - for subtraction, * for multiplication or / for division: ";
            cin >> op;
            cout << "Enter two numbers: ";
            cin >> num1 >> num2;
            if (op == '+')
                cout << num1+num2 << endl;
            else if (op == '-')
                cout << num1-num2 << endl;
            else if (op == '*')
                cout << num1*num2 << endl;
            else if (op == '/')
                cout << num1/num2 << endl;
            break;
        case 3:
            cout << "Goodbye!" << endl;
            return 0;
            break;
        default:
            cout << "Please enter valid option!" << endl;

        }
    return 0;
}