^ Use the "Magic Wand" tool, and click on the are that you want gone. In this case, all the black. After you select it, you should see a "ant line" around the area you selected. And just press [Delete]. Also, you might need to use ImageReady for a really good transparant GIF.
Or, you can just make the background the color of the boards. So you won't need to go through all that.
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