I zoomed in and showed you what it looks like when you have finished this step. The selection should be right up against the top loop. If you have completed that then do that again for the other side of the loop where the selection touches the top loop. Now you are ready for step 4. Hit this to get into the gradient editor.
Lets jump on in here.
First thign we do in step 4 is make our gradient. Look to your left if you don't know what I mean. Now in the gradient editor set it so you have a gradient like I do to the left. Now you should still have that selection on. Ok now all we have to do is get the parts in the back so that it looks like a complete ring.