No worries.
If you wish to change the images, it fairly simple.
Extract the extension using WinRar or such.
Look for the "graphics" folder, inside are 4 images;
dicetower.png
dicetower_drop.png
dicetower_icon.png
dicetower_normal.png
dicetower.png is simply the base image I used to make the other three.
dicetower_drop.png and dicetower_normal.png are the images where the dice are dragged. Both are 120x118 pixels, they can be larger or smaller, but this is what I used.
dicetower_icon.png is the icon that shows in the chat window, it is 60x59 pixels. Again, could be any size, but this size seems to be best.
So long as you rename your files to match these, it should work fine.

