[Haskell-beginners] main

Hi, I must be doing something wrong when I run a program it comes up on the screen as OK module loaded Main *Main> But it will not do what I program to do. What do I enter after *main> I tried putting in the arguments but ot just returns the arguments. For example: signum x | x < 0 = -1 | x == 0 = 0 | x > 0 = 1 Enter 5 it returns 5 What have I missed? Regards John