Lispworks

How do I call a function in a file in Lispworks? Say I've created the file test.lisp with: (defun double (x) (* x 2)).
Now I want to compile this file and fill in some value for x for the function double.
Do I do this in Output or Listener? And how? Because I've tried both..

I expect it's the same for Lispworks as for other lisps: you need to evaluate the file, to define that function in the running image, then call the function.