To be more specific, your son first has to become a PR himself. He then needs to make enough income for three years in a row to meet the income requirements of the parent / grandparent sponsorship program. He will then have to enter a lottery and wait to be selected as a sponsor.
Not until he has been PR for at least 3 years and meets minimum income requirements. Then you enter the lottery and hope you will be selected. Some people are never selected and many wait years. It is a popular program with only about 20,000 selected per year with hundreds of thousands of applicants.
