After clicking the icon, the command prompt will say “_circle Specify center point for circle or [3P/2P/Ttr (tan tan radius)]:”. Although the message seems very long and doesn’t make sense, AutoCAD is just asking you to specify or to point your cursor to any place on the black screen. It will be the center point of the circle your are about to draw. The message in the bracket  also have a meaning and will be used on drawing shapes or object (which I’ll discuss later) but for now just concentrate on how to draw a simple circle. After you picked a point in the center of the screen using your mouse and pointing your cursor, click the left mouse button. You will see on the screen a circle and as you drag the mouse up and down, the size of the circle changes (See Fig. 2 below). Then AutoCAD will ask you again as you see in the command prompt “Specify radius of circle or [Diameter]:” which is only telling you to decide what dimension of the circle you wanted to draw. If you are not concerned about the accurate dimension and just wanted to draw a circle, just pick any point until you are satisfied of the size of your circle. Look at the figure below, the cross thing there is your cursor where you can just left click your mouse and you already have a circle. If you click it, the command will end and there you have it, a circle.
But, if you want to specify the size, lets say, 1 or 2 units, just repeat the steps above and type 1 or 2 on the command prompt “Specify radius of circle or [Diameter]:” (see Figure 2) and press enter on your keyboard. That isn’t hard, isn’t it?
Just remember, “A journey of a thousand miles begins with a single step.”