Hello! My name is***** you for your question. I'm reviewing it now, and will post back again shortly.
Your son is not currently admissible to Canada. He will need to undergo what Canada immigration calls rehabilitation through them before he can submit his application.
Here is a link to the information that you will need about this process:http://www.cic.gc.ca/english/information/applications/guides/5312ETOC.asp
Unfortunately, the process is complex and if possible it would be by far better for him to retain an immigration lawyer in Canada. As well, this process will take over a year.
I hope that helps as a starting point.
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Is there anything more I can help you with at this point in time?