CIC website has pretty good information on what all is required for tourist visa. Go through the series of questions and depending upon your answer the site would let you know what all documents are required. Once you have all the documents and form filled visit vfs centre that is closest to your place. They usually review the application before forwarding it to Canadian embassy.
Also, go through this forum wherein you would get ample information on how to fill the form.
The above does not guarantee a visa , however if your sincere in your efforts with the above and are a valid visa candidate you would get one.