Okay you can use the matchmaker, but there is another way involving the secret item HONEY.
CODE: BCBACABA
Make your tamagotchi drink the honey, then connect with a tamagotchi the opposite gender. Select present. If you select game, the honey will go to waste. The other tama has to be an adult. They will talk, then they will kiss, with hearts floating in the air. Connect a day later, they will shake their heads no. (normal) Finally one will go. The screen will turn black, there will be candles. A few seconds later, the female tamagotchi will give birth to 2 tamababies.
(God that took ages)