Georgia, if you look in the back of most home improvement magazines, you will see ads for the companies that make the parts. You can search the web, but I think that the ones who pay for the advertising like that are more likely to have a good business history and product background.
Installing the ceilings are not for first time do-it-yourselfers, in most cases. When you are talking to the tin supplier, ask them if they know of qualified installers near you. If they don't, go to the highest end commercial wallpaper store you can find in your area and ask them.