You have to be the person who is mainly responsible for the care and upbringing of the child.
This means you would be responsible for such things as watch over the child's daily activities and needs, making sure the child's medical needs are met, and arranging for child care when necessary.
If the female parent lives with the child, the government usually consider her to be this person. However, it can be the father, a grandparent, or a guardian.
You have to live with the child and be a resident of Canada for income tax purposes.