Refer to Application Guide provided on CIC.
Here's a copy in text format:
"Police certificates
If you and your family members who are 18 years of age and older and are not permanent residents or Canadian citizens have to provide:
a valid police certificate, or
police clearance, or
record of no information.
These documents are to be provided for each country other than Canada, in which you have lived for six consecutive months or longer since reaching the age of 18.
Note: If you or your family members were under 18 years of age (16 years of age in certain jurisdictions) for the entire time you lived in a particular country, you do not need to provide a police certificate for that country.
The certificate must have been issued no more than three months prior to submitting your application. If the original certificate is not in English or French, then you will need to submit both the certificate and the original copy of the translation prepared by an accredited translator.
It is your responsibility to contact the police or relevant authorities. When doing so, you may have to:
pay a fee for the service, and
provide information or documentation such as:
photographs,
fingerprints,
your addresses and periods of residence in the country or territory.
We will also do our own background checks to determine if there are grounds under which you and your dependants may be inadmissible to Canada.
Please consult our website for specific and up-to-date information on how to obtain police certificates from any country.
"