The only way to obtain a TRV for Canada is to apply for one through your nearest Canadian Consulate, in your case I believe it's the Consulate of Canada, Montego Bay - phone (1 876) 952 6198. (They don't seem to have a website).
Give them a call to have the application forms sent to you and ask if you require a Letter of Invitation from family members in Canada. If you do, read this page
http://www.cic.gc.ca/english/visit/letter.asp for the details that need to be included in that letter.
The funds required will depend on the length of your proposed stay.