To create a circle, first select "Circle" from the "Science" section in the sidebar. Click on the canvas, hold down the left mouse button, and drag it out. Alternatively, you can select "Plane Geometry" 

from the "Graph Center" by clicking on the sidebar arrow. Then, hold down the shift key and the left mouse button to drag out a circle on the canvas.

If you want to draw a circle accurately, click the menu "Science" > "Circle" to open the "Input Circle Parameters" panel.

Enter the coordinates of the center of the circle (the format is "x-axis coordinate" + "," + "y-axis coordinate") and the radius.