Hi, Nancy. It sounds like you have a product that is part of a "system" that was designed by a manufacturer. They probably tried to make the whole thing easy, but you are hearing alternate ways to do things. No wonder that you are confused.
I would think that the best way was to find out how the manufacturer designed the system to be installed. You should be able to do this by finding out the manufacturer's name and then searching the web, if you don't have the URL for his site. You might go back to the home center and find out if they have the name if you can't find it otherwise.
Let us know how this comes out. There are some things that you can probably do in other ways, but it has been my experience that you usually are better off doing things the way the manufacturer suggests, particularly if you have not done it otherwise before and have experience living with the result.