Sis, maaf aku tak sure exactly yang mana tracker app you're using, ada banyak jenisnya kan! But usually ada button like "Add Child" or "+" somewhere, then you just fill in the baby's details macam nama, DOB, sama gender. Try scroll through the settings or home screen, normally it's quite straightforward! Mana app yang you pakai? A few of my mum friends use different ones, so mungkin boleh bantu lebih specific if you tell me!