The basic parameters of the selected tool are shown in the Tool Options panel. To view the full list of parameters, right-click in the Image Window.
Buttons marked with a small triangle at the bottom, contain a submenu of additional tools, which can be selected by either right-clicking or by pressing and holding the left mouse button. All the tools of this group will be displayed in the drop-down menu. Click on the desired tool with the left mouse button to select it.
You can dock the toolbar to the left or right edge of the program window or position it anywhere on the screen. Drag the toolbar by clicking and holding the upper part of the bar.