The other critical file is the one which describes the way in which the page is broken down into frames. You do not normally see this second file but it is the one which is defines the number of frames on the page and the size and properties of each frame. You can try to create a 2 frame document displaying a table of contents on the left and a questionnaire on the right. You should now load the file called Frame.htm and check that it works as expected. Any HTML between these two tags will be understood and rendered by other browsers.
Some users have a browser that can render frames but the users dislike framed documents.
For this portion of your audience, you should consider having a non-frames version of all of your pages available. This way, users who like frames can stick with them and those who don't like frames have a way to view the same content without being burdened with an uncomfortable interface. If any of these sites have moved or are not available then use one of the search tools to look for frame tutorials.