if you've just tried opening a php file with a gfx application i suggest you dont bother running a torrent tracker lol
you create the images in the graphics applications and then code them into the php scripts in standard xhtml code .. i.e
lets say you want a border round your site you may use something like this (its untested so dont copy and paste it unless you can understand it.
in the header and footer functions you would place a table something like this
Code:
<table>
<tr>
<td class="top left"></td>
<td class="top middle"></td>
<td class="top right"></td>
</tr>
<tr>
<td class="middle left"></td>
<td class="middle">
</td>
<td class="middle right"></td>
</tr>
<tr>
<td class="bottom left"></td>
<td class="bottom middle"></td>
<td class="bottom right"></td>
</tr>
</table>
then just use css to assign an image to each class