Open Paint.net and choose a shape tool from the floating tool palette at the top-left of the screen. Select the "ellipse" drawing tool for best results when you are drawing a medal.
Click the drawing tool and move your cursor to your drawing surface, then click your left mouse button and hold it down as you move the cursor across the page to form the outline of your medal. Use the "line/cure" tool o draw a medal with sharper edges.
Select the "paintbrush" or the "pencil" tool and move to the inside of your medal. Hold your mouse button down as you add freehand lines to the medal to create a design. The design you create can be anything you like. A name, abstract designs or even a particular image you want on your medal are examples of what you can draw. By using these drawing tools, you aren't restricted to any particular shape. Start new lines by releasing the mouse button after you've drawn each element and clicking again to begin a new one.