Location
Locate your Wii Number by turning on your Wii console and selecting "Wii Message Board." From there, choose "Create Message." Click on your "Address Book." The front page of your address book will say "This console's Wii Number" and will display the 16-digit identification code below that. If your address book doesn't default to the front page, you can turn pages by pressing the plus or minus key on your Wii remote.
Connect With Friends
Share your Wii Number with friends, and have them share theirs with you. From the "Address Book" screen, click "Register" to enter a friend's Wii Number into your address book. Note that both you and your friend must register each other's Wii Numbers in order for you to communicate via your Wiis. You can now type messages directly to each other's consoles, as well as share your made-up Wii characters, known as a "Mii."
Make New Friends
Online forums like MapWii.com and vgZero.com have lists of thousands of Wii gamers from around the globe looking to exchange Wii Numbers. You can register for free on these sites and start connecting with people right away.