Topic: index.html

I want to customize my gallery so i looked on the simpleviewer website and it said to EDIT THE index.html, when i open index.html in notepad/text edit it say "SimpleViewer requires Macromedia Flash. Get Macromedia Flash. If you have Flash installed, click to view gallery."

I have installed this.. and yet it still says that.. how can i change the background of my gallery?