Delegates, Why?

Possible Duplicates:
When would you use delegates in C#?
The purpose of delegates

I have seen many question regarding the use of delegates. I am still not clear where and WHY would you use delegates instead of calling the method directly.

I have heard this phrase many times: "The delegate object can then be passed to code which can call the referenced method, without having to know at compile time which method will be invoked."

I don't understand how that statement is correct.

I've written the following examples. Let's say you have 3 methods with same parameters:

   public int add(int x, int y)
    {
        int total;
        return total = x + y;
    }
    public int multiply(int x, int y)
    {
        int total;
        return total = x * y;
    }
    public int subtract(int x, int y)
    {
        int total;
        return total = x - y;
    }

Now I declare a delegate:

public delegate int Operations(int x, int y);

Now I can take it a step further a declare a handler to use this delegate (or your delegate directly)

Call delegate:

MyClass f = new MyClass();

Operations p = new Operations(f.multiply);
p.Invoke(5, 5);

or call with handler

f.OperationsHandler = f.multiply;
//just displaying result to text as an example
textBoxDelegate.Text = f.OperationsHandler.Invoke(5, 5).ToString();

In these both cases, I see my "multiply" method being specified. Why do people use the phrase "change functionality at runtime" or the one above?

Why are delegates used if every time I declare a delegate, it needs a method to point to? and if it needs a method to point to, why not just call that method directly? It seems to me that I have to write more code to use delegates than just to use the functions directly.

Can someone please give me a real world situation? I am totally confused.