Hi anas...heres my 2 cents
I just wanted to share my experience in searching my job. I started with most of major jobsites in Canada and narrowed my search to the city I'm interested in (ie AB & BC where my job is currently in demand and is listed as an occupation under pressure) and then have it fed to my email thru RSS which available in most site. Everyday I just checked my google/yahoo page to see all the new job openings for my occupation. ;D
Also, I tried this site http://workingincanada.gc.ca/welcome.do?lang=en
and this will give you all information regarding your job description, availability,wages and so on....also the current job openings in the specific province you have chosen.
Another thing, try using a Canadian Company Database which is a directory of companies in Canada. You can search by company name which employ your specific occupation...ie....engineer so i will put in the search tab..the word construction company or engineering company...then it will give you a result of names of all companies and its infos related to your search word.
http://www.profilecanada.com/