Referencing a variable in a function c++

I'm trying to make sure that I understand what the use of the ampersand to reference a variable is. I know other similar questions have been asked but I would like to see if the code example I give uses it correctly.

example code:

 // function prototype
 GetBalance(float &balance);

int main()
{
    float balance;
    bool choice = true;

    if (choice == true)
         GetBalance(float &balance);
    else
        cout << "error" << endl;

    return 0;
}

GetBalance(float &Balance)
{
    cout << "please enter the balance: " << endl;
    cin >> balance;

}

So in the main function the float variable is declared.

The function GetBalance references the variable declared in the main function. So that when the user enters a balance, the input is assigned to the balance variable.

Is this correct?

If not is what I want to do possible?

I would like to assign / pass the amount entered during the GetBalance functionto the variable "balance" declared in main().