How do i get my wii to play gamecube games?



I just bought a nintendo wii and I have 2 gamecube games im trying to play but i cant, Im beginning to think something is wrong with my wii… It plays fine with wii sports and i bought the slim controller to play the gamecube games but when the gamecube game asks me to press start nothing happens, so i try to press start with the wii wand controller and still nothing. I bought a gamecube controller and pluged it in to port one and still nothing when i press start, what am I doing wrong please help me im getting fustrated,