Game Cube difference
GameCube had much smaller disks than the Wii, called "mini disks." Wii games are more of the standard CD size. This is one way to easily tell the types apart. The GameCube controllers are also different. The GameCube controllers actually plug into the console with a little round plug on the end of a wire, unlike the Wiimotes that are remote. The GameCube controllers are also larger and oval shaped, as opposed to the rectangular Wiimote.
GameCube memory cards
The Nintendo Wii is a thin, rectangular white box that sits on a metal case in order to stand upright. On top of the case, there are two panels that pertain to GameCube. There are white covers on these panels that open to one side. The shorter panel is a place to put GameCube memory cards. GameCube didn't have its own internal memory, so it used squareish memory cards in order to save your progress on games.
Game Cube on the Wii
The other panel , when opened, has four circular holes in it. This is where you will plug in your GameCube controllers, directly into the top of the Wii by lining up the plug properly with the whole where it will fit. You will need to load from one of the memory cards when your game starts to use any saved date.
GameCube on the Wii
In order to use one of these controllers to play a game, you must first turn on the Wii with a Wiimote by pressing the "power" button. Plug in your GameCube controller into the first circular plug outlet at the top of the Wii. Put your GameCube mini disk into the Wii disk slot. It should fit normally, just like a Wii game. Once you've done this, one of the squares on the Wii main page, usually the one in the top left, should read "Nintendo GameCube" with the symbol there, or whatever the title screen of the GameCube game you're playing is.
Playing your Game
Click on the game square by moving your Wiimote to control the hand cursor on the screen over to it and then hitting the "A" button on the Wiimote. The title screen should now fill the screen with the options "Wii Menu" and "Start" appearing on the screen at the bottom. Move the Wii cursor to "Start" and click the "A" button. You should hear a tone, and your GameCube game should begin. Put your Wiimote aside, and you can now use your GameCube controller to play the game.