This is not a user setting.  It is a way for you to put code in your skin and make it more dynamic.

If this code is in your skin:

And you have an image in your skin folder named "Home_Banner.jpg", then the skin will show that image when the Home Page is active.

You would want to make sure you had an image in the skin directory for every page if you did it this way though.

If you wanted to just have a few of the pages show this image and have a default for the rest you could put this code in your skin where you want the image:

                                    Response.write SkinPath & "home_logo.jpg"
                              Case "about us"
                                    Response.write SkinPath & "about_logo.jpg"
                              Case Else
                                    Response.write SkinPath & "default_logo.jpg"
                        End Select %>" alt="" />