The 2MIDI GUI (Graphic User Interface) is quite a bit different from the usual Windows GUI, so it may take some getting used to. You can identify a control by the fact that it lights up when the mouse is over it. If you right click a control, a little "bubble" description of what it does will be shown (it will also be shown if you leave the mouse over the control for a second). The various controls are listed below.

the current option page
option page button
enabled button
disabled button
ON switch
OFF switch (also disabled switch)
ON channel allocation switch
OFF channel allocation switch
enabled edit box
disabled edit box
slider bar (left = lower, right = higher)

2MIDI allows you to assign any keyboard shortcut to any button or switch. This allows you to personalize the interface for maximum speed and ease of use. To edit the shortcuts simply switch on the CUTS option to get into cuts mode, all buttons and switches will then go plain white with the current keyboard shortcut displayed (if one is set for the button/switch). To edit a shortcut, move the mouse over the button/switch and press the key for the shortcut. You can use the shift, control and alt keys in combination with the standard keys. To remove a shortcut press esc while over the button/switch. After you've finished editing the shortcuts, click the CUTS switch again to get back into the normal mode.