How to I add a headergrafic?

[JQUEST]

You can put the header image on


<TABLE cellSpacing=0 border="0" cellPadding=0 width="100%" >
<TR vAlign=center>
<td align="right" width=212> here You header including logo</td>

Or You can add as background like
<td background="here your background" >Logo</td>

I want to add a graphic behind the "SIGNUP / LOGIN" links in the header.
I uploaded my image, added a "signup" class in style.css, put the login links in a table with the signup class tag and nada...

I think maybe my problem is the css...? (I'm fairly sure the codes are right though)

Any ideas why this isn't working?

Thanks for your help!