You have to fill out the PIF (personal information form) after you arrive in Canada.
You have 28 days to complete the PIF. The form is long (13 pages!) and it must be filled out in English or French. You may need help, so you should contact a lawyer or consultant . You have to take it or mail it to Immigration and Refugee Board office. After your PIF is received by the IRB, they will review it and then contact you.
Download the PIF (pdf)