The bottom background is set here:
background: url("images/body.png") repeat scroll 0 0 transparent;
And the top -- which is essentially on top of the above, is set here:
background: url("images/bl.jpg") repeat-x scroll center top transparent;
Unless there is a theme option to change them, the easiest way to do it would be to use different images -- but use the same name and replace the current images in the same file location.
The green is set here:
background: none repeat scroll 0 0 #1E8745;
border-radius: 0 5px 5px 0;
padding: 5px 10px;
Do be aware that it's recommended that changes to your theme be made in a Child Theme or using a Custom CSS option or plug-in so that changes won't be lost when the theme is updated.
Also, just so you know, bumping is against the forum rules and will typically be removed by a moderator...