I don't think you need special software, you will probably just need to go to the website and download the graphics image for the buttons background.
From there most of the visual stuff are all css.
Thus, you will need to learn css.
Otherwise, download the page source and resources like js, css, jpg etc to reproduce the page on your own machine.
From there edit as you wish.
In addition, use FireFox with Firebug to get hold of how each element is styled and you can learn from it too.
An alternative, if you don't need to follow the style 100%.
You can create some pretty themed web page by just importing some themed css from e.g. jquery ui or dojo and you can create nice button pretty quickly.
hxxp://jqueryui.com/themeroller/
hxxp://dojotoolkit.org/reference-guide/1.7/dijit/themes.html
hth