Sociable: How to add an imagine instead of a TAGLINE?

Hey Folks.

Here’s my current tagline: http://www.PUMATALK.com/blog

And basically what I want to do is add an imagine rather then the text which is defined in the setting here: http://i44.tinypic.com/34g8znq.png

What do I need to do?
Please help.

Thanks,
-Joey