Oh, and here's how to get your Wii code, and how to add a Wii Friend:
When you are on the Wii Menu, go to the Wii Message Board (lower right letter button), then from the buttons on the left, select the second one (the one with the pencil).
Once you're there, at the right you'll see the Address Book, select it to see which Wii Friends your Wii Friend code (or Wii Number), if you select Register, then you can add a Wii or an E-Mail.
To register a Wii you must type in the Wii Number of your friend, and then be sure about he added you, then you can be Wii Friends.
To register an E-Mail Address you must enter the E-Mail Address you wish to add.
Then you have to be sure about the owner of that E-Mail address adds this to his contacts list:
w################@wii.com
You must change all the #'s to your Wii Number, in my case, it's like this:
w0042346143009424@wii.com
Then the same owner of the Address will receive a mail by Nintendo, to add you, he must just reply to that message, once you've done that, you will become his friend and you will as well be able to send him messages from your Wii!
Both processes take some time, but becoming a Wii Friend is way faster.
I hope it helps, and I expect to become your Wii Friend, too!