If no additional methods (like dpkg-mountable) have been installed then selecting [A]ccess will provide the six access methods: cdrom, nfs, hard disk, mounted, floppy, and ftp. Each of these ``methods'' needs slightly different information. The goal is to find the Packages file for the various pieces of the distribution.
The top half of the screen, topped with the red title bar, shows the menu items. The list can be traversed with the arrow keys and enter selects the item under the highlight bar.
The bottom half of the screen is bounded by blue highlight bars. The top bar names the access method currently highlighted. In between the bars is descriptive help information about the highlighted selection. The bottom bar indicates the percentage of text viewed, and the key that will change the current text position in the window.
This is a common pattern in dselect. The upper portion of the window i s where the activities occur and the bottom half provides additional information to help make the choice.