To insert a new control, click on a point in the main Book Designer window where you want to put a control and press the desired control icon. As soon as the control is inserted, its html source appears in the "HTML fragment editor"

allowing you to edit the control manually.
To edit an existed control manually, select it by the mouse and run "HTML fragment editor"

. Most part of controls can also be loaded to "HTML fragment editor" by double-click.
To move an existed control, point the mouse cursor on a control, press left mouse button and holding it, drag the control to a new position.
To resize an existed control, click on it and resize it using small white quadrates at the control border.