You can find it in the Document Checklist file. You should submit all your family members' photos.
www.cic.gc.ca/english/pdf/kits/forms/IMM5690E.pdf
Photo Requirements
Include six (6) photos for each member of your family, whether accompanying or not, and yourself.
Follow the instructions provided in the section How to Complete the Forms of the application guide and in Appendix A:
Photo Specifications. Photos must have been taken within six (6) months before application submission.
On the back of five (5) of the photographs, write the name and date of birth of the person who appears in the photo as well as the date the photo was taken. Leave the sixth photograph blank