edit transform function

My digital camera has a tendency to distort as the image nears the outside of the frame. Is there a photoshop function that can correct this? I have tried the Transform functions (skew, distort, etc), and correcting half of the image is easy by dragging the corner grips away from the center to stretch the image, but, when I go to the opposite end of each given side, the distortion returns. The problem is the grip at the midpoint on each side moves with the rest of the side when using this feature. Is there a transform feature or other command that does something similar, but the midpoint grips stay stationary, basically taking the rectangular shape of the image and making it into an hourglass or four pointed star?

By the way, how do I include an image with this thread? I am new to this site!

There is an Insert Image and Insert Hyperlink funktion in the message writing tools. Use them.