Note that title and filename are two different things. If you do nothing here, you will probably wind up with the ugly, default web gray background. There are different reasons for different background colors. But white or another light color generally makes the most sense for pages with text. You also have a chance here to set the link colors.
Many people argue for the default of blue active links and red visited links.
Web design guru David Siegel says you should reverse them. You might also want to save again. You should always save your work periodically. What Netscape Composer is doing for you is writing the HTML codes that allow you page to be read around the Net. You no longer need to learn HTML, but it is useful to see how it works.