Jared, all you need is an editor that supports saving in .png with transparency. I usually use GIMP.
To make the background transparent (if it already isn't), first I select the color I want to be transparent by the select-tool -> select by color, and after that I choose Colors -> color to alpha. If I don't select the color I want to make transparent and just use "color to alpha", it makes that color totally transparent and the rest of the colors translucent, which isn't desirable.