'A' button - all the way to the left of your tamagotchi
'B' button - the button in the middle
'C' button - the button all the way to the right of your tamagotchi
to enter shop codes, go to the game icon, then go down to the shop, then click 'A' button repeatedly until the shop owners expression changes, then put in the code according to the letter and the buttons.
to put in passwords, go to the game icon and go down until you see password the press the 'B' button to go in. the push in the password