How can my sister apply for me to go to Canada? My brother-in-law just applied for it for her.

If it is a tourist visa, your sister should be able to invite you to Canada, as long as you can prove that your life in China is stable and you will not stay in Canada.

But if you're talking about immigration, there's nothing you can do. Your sister can only support your parents, not your immigration. Unless your sister is a resident of Saskatchewan, Manitoba or Alberta (which has strict requirements for applicants), after meeting certain living and economic conditions, she can sponsor her siblings and other indirect relatives to apply for immigration.