Constipated baby

Amber • 👼 10/14/14 👶 8/8/19 👶 9/4/20 🧒7/1/22
I am a new mother. My baby is 3 weeks old and she is constipated. Hasn't had a a bowel movement since yesterday. I have read on the Internet to give a baby a teaspoon of Karl syrup but I am very scared to give it to her. What should I do to help her little belly?