Instructions
Boot up the Wii.
Select the "Mii Channel." It's the second channel from the left on the top row of channels at the home screen.
Hit "Start," which will bring you to the Mii main screen, where you can make, edit and arrange Miis.
Select the "New Mii" icon, which is the smile face icon with the plus sign on the left side of the screen.
Select your Mii's gender.
Choose "Start from scratch," which brings you directly to the Mii customization screen, or "Pick a look-alike," which will let you choose one face from a group of pre-made faces. Choosing a face will bring you to a new screen with similar faces. Choose one to go to the customization screen.
Choose a head shape, skin color, facial markings and blush.
Select the hair tab to choose a hair style and color.
Select tabs for eyebrows, eyes, nose lip, facial hair and glasses to pick the styles, colors, size and position.
Go back to the first tab on the screen. Create a nickname for your Mii, mark it as favorite if you want, then choose a birthday and favorite color.
Hit "Quit" at the bottom of the screen.
Select "Save and Quit." Your Mii now will show up on the Mii main screen walking around.