The upper frame consists of indexes into topics in the right frame. Clicking on a link will take you to the chosen website. After selecting a link, the desired website will appear in a separate window. The window may appear behind the Navigator window. The separate window solves a few problems with inconsistencies with various browsers, plays well with other websites which themselves have frames, and allows the bookmark mechanism to work as expected.
Some activities span a number of topics.
Use your browser's FIND function to locate items of interest. The FIND function's behavior is slightly different on each browser. This one is sneaky but helpful. Use this option wisely, understanding the consequences. The 'Navigator is designed to pack a large amount of data into a small area, which accommodates laptops and WebTV fairly well.