Here's where to change the stacking order for a shape.
To change a shape's position in the stacking order, select the shape, and then point to Order on the Shape menu. You'll see four options. Bring to Front or Send to Back move a shape all the way in the stacking order.
If your stacking order comprises many shapes, however, you may not want a shape to go all the way to the front or the back of the order. In that case, you can move the shape forward or backward a step at a time, by choosing either Bring Forward or Send Backward.