How to potty train my 3 yrs old girl?

You can do this in stages. First stage is to remove her nappy during the day and monitor her body reactions. You will have a feel anyway how she behaves when she needs to do number one or two. I used a dipper and made my son pee there. So he knows he needs to look for the dipper when he needs to pee. When he looked like he needed number two, I would bring him to the toilet where I have the kid toilet seat installed. Eventually he looked for the toilet when he wanted to do number two. Second phase is to train at night. You wake up your child to owe until she will wake up herself to pee.