The Inkscape window is laid out with three bars at the top, one on the left, and one at the bottom. The very top menu is the Menu Bar, containing advanced features. The next bar down is the Command Menu bar. It has buttons of commonly used edits such as file options, undo, copy, clone, group, etc. Underneath it is the Tool Controls bar, which changes depending upon which tool is selected. The tools can be selected from the Tool bar, on the left. To find out what each button does hover/mouse-over an icon and a tooltip will pop up.
All these bars, except the Menu Bar, can be "torn off" and moved around. To move either of the top two bars (Commands or Tool Controls), click and drag from the left end. The Command bar will turn into an arrow icon, which can be clicked for a dropdown menu. To tear off the Tool bar, click and drag the top edge. To re-dock any of these, simply drag them back to their home positions.
Each tool has a keyboard shortcut---usually an F-key and an alternate, letter key. Selector is slightly different, in that its shortcut, the Space bar, is a toggle. When using any other tool, you can hit Space to get the Selector, and then Space again to go back to the tool you were using. The Selector is used to select, resize, rotate, and move objects.
Go into Inkscape, and try out different shape tools by clicking their icons in the toolbar, or by pressing their keyboard shortcuts. Then, click and drag with the mouse to try making shapes. The shape tools are Rectangle, 3D Box, Ellipse, Star/Polygon, and Spiral. The other tools are slightly more complex, and will be explained in the chapters on Path Editing and Other Tools. Pencil is very intuitive: just click and drag to draw a line.
At the bottom of the screen is a bar of swatches, and the Status bar. Select a shape, and click one of the swatches. The shape's color will be replaced by the swatch color.
You can pan the canvas with Ctrl + arrow keys, or by clicking and dragging with your middle mouse button. Of course, scrolling with a scroll-wheel works as well. You can toggle the scrollbars with Ctrl-B.
To cycle between Inkscape windows, use Ctrl-Tab. To cycle backwards, use Ctrl-Shift-Tab.