KGeo can roughly been divided into three modes. First of all there is the construction mode. Then, there is the grad mode in which you can drag constructed object around and which shows you the immediate effect of this movement. For example, if you think of the circle of Thales and you move the point on the upper half circle, you will see that the angle remains a constant 90 degrees. The third mode is the trace mode. You can mark points, so that they leave a trace when they move, i.e they 'leave a trace' where ever they moved over and you can see the way an object went. What follows now is a more detailed description of these three modes.
On the left side of the main view you find all the tool neede to draw geometrical objects. The first button, for example, shows a point and that is exactly what is draws. If you click on this button and then on the main view, a point will be drawn.
All the tools are organised in groups to help you find the right tool you need. If you choose the segment tool, for example, you can click on two different areas of the main view and a segment will be drawn between the two points. If you choose the segment tool a second time, you can also click on existing points and thus construct segment between points you have created earlier.
If you are not sure what a tool is doing just go over it with the mouse pointer and ait for a second. The tool tip will tell you exactly what you can do with it.