When your Tamagotchi turns into an adult, about a day after, you will get an important info message saying you graduated elem. school and then right after that message you will get another one with the job listings. In order to get a job you need to have at least 50 of a certain skill.
If your Tamagotchi retires and turns into an oldie, it can still mate with another oldie of the opposite gender via connection.
^_^ GotchiGirl96 ^_^