When you start the device you are given an egg that will hatch into an Eevee. Then through caring for Eevee you can evolve it into any of it's evolutions. How well you care for Eevee determines the evolution of your Eevee.
Like most Tamagotchi, you can feed Eevee. This can be done either using Food or by feeding it various snacks. To feed Eevee, select the first icon on the menu. First selection is 'meal' and the other is 'snack'. Meal will fill Eevee's hunger up, and giving a snack will make Eevee happy. Eevee takes 4 meals to be 100% full. Eevee will let you know if it's full by refusing to eat any more food.
Unlike other Tamagotchi models there is no menu display to see what Eevee needs. To see how Eevee is feeling press the C button. If it needs food it will be show a swirl above it's head. If it is unhappy it will show a circle mark.
If Eevee is happy and needs no attention it will come up closer to the screen and smile.
Sometimes, Eevee will leave a furball. This is needed to be removed using the A button to clean your Eevee which makes it happy
If you have neglected Eevee or its evolutions, or the time reaches the time for it to end, rather than pass on, Eevee will return to its Poké Ball saying "Bye Bye".
Pressing the middle button will bring up the time. You can pause the Eevee Tamagotchi by pressing A + C to set the time. You can also mute the sound on the Tamagotchi if you press the A and C buttons when Eevee is on screen.
Eevee will wake up at 7am and go to bed at 8pm while its evolutions wake up at 7am and go to bed at 10pm.