We are going to edit HTML/themes/yourtheme/theme.php
Find the section starting with:

function themesidebox($title, $content) {

and copy the whole section to the last "}"
Mine looked like this: (yours may look different)

function themesidebox($title, $content) { echo "<table border="0" cellspacing="0" cellpadding="0" width="150" bgcolor="000000"><tr><td>" ."<table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td bgcolor="6699ff">" ."<font class="content">$title</font></td></tr><tr><td bgcolor="ffffff"><font class="content">" ."$content" ."</font></td></tr></table></td></tr></table><br>"; }

Paste it back in and rename it to themesidebox2

function themesidebox2($title, $content) {

Now, for testing purposes, we are going to change the color.
The MIDDLE table "bgcolor" determines the background of the box top.
In the example above, the color was 6699ff. I changed it to 000000.
Your theme may set color to $bgcolorX, just change that to 000000 for now.

Ok, now we have a box definition we can use just for the Modules block.

Save the file to your site, and test.
Make sure you have selected the right theme in Your Account! (see Figure 6-7)
You should see no changes or errors! That's good.