for a tourist visa, it would really help to have an invitation letter sent to you by a friend or relative in canada, but this is still no guarantee that a visa will be granted.
You submit this letter, together with photocopy of your sponsor's ID (government issued), tax certificate, bank account, plus the form/s you have to fill up, bank statement, job cert, letter from your boss that you are being allowed to have this vacation, to the Canadian Embassy (for pick-up)
Now, i dont particulary know your scenario, the example above were the docs my brother submitted when i asked him to come here as a tourist, this granting i will shoulder all his expenses, including airfare, board and lodging, health insurance.