19831983,
Yeesss, .........You heard right....
A COVERING LETTER : will do a world of good for your case. In the letter you can tell them who you are, why you want to move to Canada. And if you can, also mention of what use you will be to your newly adopted country.
A LETTER OF REFERENCE / LETTERS OF REFERENCE : these you can get from people with good standing in society or someone who holds public office. In the letter they would have to state that they know you well and for how long, they could vouch that you are a person of good character.
WORK EXPERIENCE LETTERS : These letters you get from your previous employers stating the number of years you worked for them your position, job description, how skillful you were at your job, your interpersonal skills with your peers, immediate superiors, customers, dealers etc., and the salary you drew at the time of leaving.
IN ADDITION to your Work Experience Letters your boss may want to give you another letter saying how much they enjoyed your work when you were in their employ and also stress on your character.
LETTERS OF COMMENDATION : These are letters you get from somebody who holds public office, or your boss for acts or deeds of bravery, going out of your way to help another human being etc.,
These are just a few thoughts & I hope it is of help.
Mike