Step 11 Select the duplicate ellipse and the red rectangle and send both the the back (Ctrl - B)
NOTE: To bring an object to the front use Ctrl - F Just remember F for front and B
for back)
Select the duplicate ellipse and then select the Transparency Tool. From the drop down list on the Infobar select Linear. Leave the
Transparency Type set to Mix. Reposition the fill path as shown so the top and bottom extend a little above and a little below the actual ellipse.
Step 12 Using the Rectangle Tool draw another rectangle for the wall behind the lamp to the size shown. Using the two
colors shown, apply a Circular Fill as shown.
With any luck your
illustration should look like the one shown on the left.
So what have you learned?
Was this tutorial illuminating? Was there anything that was not clear?
Step 11 Select the duplicate ellipse and the red rectangle and send both the the back (Ctrl - B) 
Step 12 Using the Rectangle Tool draw another rectangle for the wall behind the lamp to the size shown. Using the two
colors shown, apply a Circular Fill as shown. 
With any luck your
illustration should look like the one shown on the left.