The most basic sidebrain operations are beginning and ending tasks.
To begin a task, enter the command sidebrain-begin-task. You will be prompted for some text describing the task. A window or frame will appear displaying the current task stack, with your newly entered task on top. (See Controlling the display for how to control whether sidebrain uses a frame of its own, and other control factors.)
To end the topmost task of the stack, enter the command sidebrain-end-task. The task will be popped from the stack.