Reference: Configure and Test HTTP Transfer Command
This window lists any links to other web pages or files that are found in the file specified by the source URL (From field). You create this list by clicking the Get Links button. You select a link from this list by double-clicking it. This action updates both the From and To fields, creating a prospective transfer. Clicking Get Links again will refresh the display with links from the new source URL. In this manner, you can traverse a web site to find the particular file you need.