Please read the guide. There are also pictures.
http://www.cic.gc.ca/english/information/applications/guides/5609ETOC.asp#appendixA
The photos must:
•show a full front view of the person's head and shoulders showing full face centered in the middle of the photograph;
•have a plain white background;
•be identical (black and white or colour) produced from the same untouched negative, or exposed simultaneously by a split-image or multi-lens camera.
The photos must:
•measure between 25 mm and 30 mm (1″ and 1 1/5″) from chin to crown
•have a 35 mm x 45 mm (1 3/8″ x 1 3/4″) finished size
•bear the date the photo was taken (not the date the photo was printed) directly on the back (stick-on labels are not acceptable).
