After you submit sponsorship application CIC will review and determine if you are eligible for sponsorship. Make sure you complete the application and provide all needed supporting documents. Missing documents or incomplete forms can result in unnecessary delays or refusal.
A lot of information is available on the pages available at the links below:
http://www.cic.gc.ca/english/information/applications/family.asp
http://www.cic.gc.ca/english/immigrate/sponsor/relatives-apply-after.asp