There are two exams that you can complete free of charge at any Transport Canada Examination Centres. One on operations/navigation/regulations/flight planning and one on meteorology. Once you have the two exams completed with 70% or above, you can apply to airlines where they will then further train you. I'm not 100% sure but I think the dispatcher license is granted after you are employed and have completed company training. First step would be to to pass the two exams. Here's a link to the study guide:
http://www.tc.gc.ca/Publications/EN/...R/tp12513e.pdf