To add images you add it to your skins/custom/_main.php file. Look down the file and you will see a note indicating START OF SIDEBAR. Under it you will see several bits that identify individual sidebar components

<div class="bSideItem">
blah blah blah - stuff goes in here
</div>

You don't HAVE to use a div but that's how you will get your little dividing lines to happen. To do images first put your images in the blogs/img folder then try this:

<div class="bSideItem">
<p class="center">
<a href="URI for linking" title="mouseover text"><img src="<?php imgbase() ?>imagename.gif" alt="mouseover text" width="XX" height="YY" class="middle" /></a>
<img src="../../img/flight/imagename.gif" alt="mouseover text" title="mouseover text" width="XX" height="YY" class="middle" />
</p>
</div>

Note the two different ways to get your image to show up. The first one is linked, the second is not, but either method for the image source will work with or without links. You could also put the image in skins/custom/img and call them up with src="imagename.gif" if you prefer. To continually add new ones to the bottom you just place the new image tag (or div with image tags inside) beneath the previous stuff.