1. With paint.net open, make sure your tools bar is open. It is the window box that is usually on the left side of the screen that looks like this:
If you do not see it, then direct your vision to the menu bar at the top of paint.net, and click on Window. A drop down menu will appear. Click on tools. Now, the tools box should be available.
2. Look in the tools box that you just opened. On the very bottom-left of the tools box, you will see an oval shape. Click on that.
3. In the white drawing space, left-click in a spot and hold it. Now drag your cursor to another spot, and let go of the "click" or mouse button whenever you are pleased with the circle.
There you have it, a circle!