About screenshot: two way, first using the html code provided by imageshack click on the html button here and past the code you copy on imageshack; second use the direct link to the image like http://whateverurl.com/image.jpg copy it, click on the image button here and past it.
About start button: Start button is usually an image with 5 states. So you should have something like that:

With in order: Normal, Pressed, Disable, Mouse Over, Focus & Default States.
(You can download the picture by right click, save as... )
the usal size is: 380x30 pixel
you'll may need to play with the margins to make it fit correctly