Copy this code and put it in an "HTML" gadget. If you need detailed instructions go HERE.
<style type="text/css">body {background-image:
url('https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihZwcYMEPKuklJUtcgjGwjFRfelpzBqDSFWqlMwxLar4wLN-JT-7JUdhdo0CD40aS8L3KRQkgm4V7nqEaVE1CK6CdU1Y1yoHuUe1ov-YWsjp2ueEWQtu8pSU0C-qsCTrNer0DWP-fA0zw/s1600/Slide6.JPG');
background-position: top; background-repeat: no-repeat; background-attachment: fixed;
}</style><div id="tag" style="position:absolute; top:30px; left:0px;
border:0px;"><a href="http://www.designsbyfarmgirl.blogspot.com" target="_blank"><img
border="0"src="http://i1213.photobucket.com/albums/cc463/MNFarmGirl/backgrounds/DBFGLogo.gif" width="185"/></a></div>