The Deform tool.  Many people have stated they have problems with this tool.  It is a very useful tool for adjusting a selection on a layer.  To show this off, I'm going to really deform a clock that is first shown as normal on the graphic.  The clock is a tube image that has been placed on its own layer.  Once I placed the clock on its own layer, the Deform tool lit up, became active.  You may have noticed that the Deform tool is one of the tools on the palette that is not always lit up, active.  You have to give it what it wants for it to become active.  In this case, an image on its own layer.

When I click on the Deform tool, the image is surrounded by a box with little squares where I can adjust the image.  It can be stretched up, in, out, down, etc.  Move the cursor around and the Clockwise symbol will come up.  You can rotate the image when you see this.  If you want to move the image you are deforming, move the cursor around until you see the Mover tool appear.

So I strectched the clock up and inward.  You pull or push on the squares.  Then I rotated to the right when the Clockwise symbol was showing.  If you hold down the Ctrl key on the keyboard, then position the cursor over one of the edge squares, you can stretch out one side like I did on the third image below.  The fourth image shows the result.  You will see a Trapazoid appear when you area holding down the Ctrl key and have the cursor over one of the edge's box squares.

Hold down just the Shift key on the keyboard and put the cursor over one of the square boxes on the edges.  You will see a Skew image appear.    This is more of a straight line Skew versus the little carosel horse above.