[Melvin the Dork]

Hey, I am helping a friend with a website and I have hit the same snag she has. Meaning I am not much help at all.
What I need to know is this; I have an image that is to be used as a horizontal bar for separating page sections. What I want is just the design, and no background.
Forgive the poor illustration, -----O-----
That is how it looks for the most part. Whatever I do makes the background white, not clear. What am I doing wrong?

Thanks
Mel