Well, really, you can put it wherever you want the picture to show up.
In my case, I edited the header, and put the variables right under the logo.
All you have to do is put the variable in where you want it. You can format it if you want, too.
I have mine in a table like this:
Code:
<table border="0" width="$stylevar[outertablewidth]" cellpadding="0" cellspacing="0" align="center">
<tr>
<td align="center">$randpic1</a></td>
<td align="center">$randpic2</a></td>
<td align="center">$randpic3</a></td>
<td align="center">$randpic4</a></td>
<td align="center">$randpic5</a></td>
<td align="center">$randpic6</a></td>
<td align="$stylevar[right]">
</td>
</tr>
</table>
That puts 6 random images in a row across the top of my forums just below the logo and above the forum content.