Select the Ellipse Tool, and holding down the Ctrl key (to constrain the ellipse to a circle) click and drag a circle that is 120 pixels in diameter.
TIP: You can modify the size of the ellipse by changing the size on the Infobar.
Select the circle and send it to the back (press Ctrl - B as in Back).
Using the Rectangle Tool, draw a rectangle 300 pixels wide by 50 pixels deep and center it on the bottom of the larger rectangle.
TIP: You can also drag-resize the larger rectangle and right click to drop a duplicate.
Using the Rectangle Tool, draw three small rectangles to the sizes shown on the left. Position them as shown.