Pilot Fish: Change Background Color/Texture

Hi.

I’m trying to change the texture of Pilot Fish default background from solid white (#fff) to a texture I downloaded from subtlepatterns.com.

I’ve already uploaded the texture (which is a .png file) to my FTP file via Bluehost, but I can’t seem to get it to appear on my site. I played around in the CSS file. I also attempted to play around in the function.php. Any clues as to what I’m doing wrong?

Here’s my site: http://www.taralconley.org/

Thanks in advance!