Settings window:

You can open Settings window either by clicking right mouse button on To Do List icon in system tray and selecting "Settings..." or by clicking Settings button on main window of Biromsoft To Do List (appearance of this button depends on selected Skin.

Start with Windows - Biromsoft To Do List will start every time you turning your computer on. You will not have to launch To Do List manually each time.
Minimize on start - To Do List will not show up on start, it will hide itself in system tray until you click on its icon.
Transparency - Supported on Windows2000 and XP only. To Do List will be half-transparent in a few seconds after you will move out your mouse. This will allow you to simultaneously see your desktop (or any program behind To Do List) and your task's list.
Skin: - you can change current skin here.
Sort by: - you can change order of tasks on task's list here.
Done task put in bottom - All completed tasks will be on the bottom of the tasks list.
Show Grid - Will show grid on tasks list.
Show Due Date - Will show Due Date row on tasks list.
Show Priority - Will show Priority row on tasks list.
Show Category - Will show Category row on tasks list.
Show Reminder Icon - Will show Reminder icon if task's reminder is activated, also in a row.