Where to find user manuals?

Is there a website that I could visit to get a user manual for my digital camera? I have both a Canon and a Nikon, both without manuals.

Sure, go to the Canon site. You'll find pdf version manuals for every camera made by Canon there.

Here is a link to all the Nikon user manuals

http://support.nikonusa.com/...8#Anchor-9

I have not found such a page on the Canon website, so you will have to find the individual manuals from each camera page.

http://www.usa.canon.com/...lr_cameras

Most manufacturers have downloadable manuals (PDF files) in the support/download section of their websites.

Both Canon and Nikon do for sure.

Go to the official Canon website for the Canon manual and go to the official Nikon website for the Nikon manual. That would be the first logical step you should have made.