2) Click the envelope icon in the corner, and there will be three large things in the centerish region. The rightmost should be the "Address Book" or something like that. Click it.
Now, you should be brought to a fairly barren page (since it seems you haven't added anyone either). Press the "-" button, or "flip a page back" (move the pointer to the left, there should be some sort of arrow to progress backwards).
Your Friend Code's right there.
3) Go to the "Address Book" and in the right corner, there should be a button that reads "Register". Click that, then click "Wii". Enter the Friend Code, your nickname for the person, attach a Mii to the addition if you want, and you're done. You can only send messages or memos to the other person once you've both added each other, and after a short wait (assuming the other at least has standby mode on).