I'm assuming this is Tamagotchi Connection v2 or v3, because they're popular. V1s seem to have died into extinction. Here's a run through of the icons and stuff for help...
A- is the far left button. Scroll through options/letters/numbers with this.
B- is the middle button. Select options.
C- is the far right button. Cancel things with this.
Status meter- First icon. Check hunger, happiness, training (don't worry about this if you're a newbie), name, age, weight, gender, generation, points and username (if v3).
Feeding time- Second icon. Choose between Meal, Snack and Treat (if v2, don't worry about this).
Toilet Icon- You guessed it.
Game Icon- v2 has Game, Shop and Item. Forget Shop and Item for now. Game has four games on v2, they are pretty easy to figure out how to play. v3 has Game, Item, Shop, Password and Souvenir. Forget all of them but Game, they have 6 easy-to-learn games.
Infrared Connection- Choose version of Tamagotchi to connect with and connect with another Tamagotchi using the infrared port at the top of the egg.
Discipline- Forget about this for now.
Medicine- Whenever a skull or tooth appears above your Tamagotchi, choose this to cure your Tamagotchi. Sometimes you need 2 doses.
Lights- Turn lights off when Tamagotchi is sleeping. They turn on automatically when Tamagotchi wakes up.
Notebook- v2 has Friend and Present. Forget present, Friend has the list of Tamagotchis you've connected with. v3 has Friend, Present, Point and Family. Just stick with Friend and you'll be fine.
Attention- Unselectable, will light up when Tamagotchi needs something.
Tamagotchis may sing (adult and teenager) or simply roll (child). Near Christmas there is a talking tree. During March, April and May they plant flowers. I wonder why?