[O] Cannot get capture to work on Emacs 24.3.1 - Org itself does work

[George Taylor]

I cannot get Capture to work.

Summary:
I have successfully installed and used emacs on my laptop, and am happily using 
Org mode.
I cannot get Capture to work. I have edited my .emacs file, but I am getting an 
error when starting emacs, and C-c c does not work.

Detail:
I have installed 

24.3.1 (i386-mingw-nt6.1.7601) of 2013-03-17 on MARVIN on my laptop running 
Windows XP (Japanese).

Org-mode works.

I edited my .emacs file per 
.../manual/Setting-up-capture.html#Setting-up-capture
by adding

(setq org-default-notes-file (concat org-directory "/notes.org"))
     (define-key global-map "\C-cc" 'org-capture)

Now, when I start emacs normally, I get the warning:

...: An error occurred while loading `c:/home/.emacs':

Symbol's value as variable is void: org-directory

To ensure normal operation...

I restarted emacs by running 

runemacs.exe --debug-init

and got the foolowing Backtrace:

Debugger entered--Lisp error: (void-variable org-directory)
  (concat org-directory "/notes.org")
  (setq org-default-notes-file (concat org-directory "/notes.org"))
  eval-buffer(#<buffer  *load*> nil "c:/home/.emacs" nil t)  ; Reading at 
buffer position 1168
  load-with-code-conversion("c:/home/.emacs" "c:/home/.emacs" t t)
  load("~/.emacs" t t)
  #[0 "\205\262 (and a lot of other code conversions that don't seem to copy 
and paste)

I have referred to the org manual, and read the FAQ. I do not see this problem 
addressed. I hope you can help me.

Why is the variable org-directory void?
Do I need to edit some file other than .emacs?
Is there something else I should do?