Unbound variable - undefined function

[Blair]

Hello,
I am just getting started in Lisp and thought I would try CUSP. I
followed the instructions on the tutorial and other websites but for
the life of me just can't seem to run a simple "Hello World" program.
Actually, I finally got it working by loading .asd and then changing
the package to new-lisp1. But now when I put f in the export function
I can't run it from common-lisp-user and it says undefined function.

I start a Lisp project so I have my main.lisp:
;;;; 2011-02-25 12:17:46
;;;; This is your lisp file. May it serve you well.

(in-package :new-lisp1)

(defun f() "hello")

My .asd file:
;;;; 2011-02-25 12:17:46

(defpackage #:new-lisp1-asd
(:use :cl :asdf))

(in-package :new-lisp1-asd)

(defsystem new-lisp1
:name "new-lisp1"
:version "0.1"
:components ((:file "defpackage")
(:file "main" :depends-on ("defpackage")))
:depends-on ())

And def-package:
;;;; 2011-02-25 12:17:46


(in-package :common-lisp-user)

(defpackage :new-lisp1
(:nicknames :new-lisp1)
(:use :cl)
(:export

;; Exported symbols go here
f
))

Do I need to load the ASD anytime I make a change to my program?

Any links or help would be appeciated. Just finding it difficult to
learn Lisp and Eclipse at the same time. I know it all has to do with
namespaces and such but haven't got that far in my Lisp book.

Thanks for the help, cheers,
Blair