step 1. Define the structure of a delegate
public delegate string Testdelegate(string msg);
step 2. Write a function
string Testdel(string msg)
{
	Response.Write(msg+"am here....am from delegate");
	return "   hurray!!!!!   ";
}
step 3. Create an instance for the delegate
void InvokeDel()
{
	Testdelegate obj=new Testdelegate(Testdel);//passing the function address as an argument. Here the function definition should matches the Delegate definition else you will  receive an error.
	string aa="hello......";
                     string ee=obj(aa); 
	Response.Write(ee+"   am from return value");
}

try this.............

Happy coding..........................