ok, since I don't know what you tried or what your files look like so I am going to start here with the basic.
skin1/rectangle_top.tpl
Code:
<TABLE align=center border=1 cellPadding=0 cellSpacing=0 width=99% height=99% bordercolor=#000000>
<TR>
<TD valign=top>
skin1/rectangle_bottom.tpl
Code:
</TABLE>
</TR>
</TD>
This SHOULD put a 1 pixel black border around EVERYTHING.