This is what you html would look like:
<div id="border_links">
<p1><a href=""> link</a></p1>
<p1><a href=""> link</a></p1>
<p1><a href=""> link</a></p1>
<p1><a href=""> link</a></p1>
<p1><a href=""> link</a></p1>
<p1><a href=""> link</a></p1>
<p1><a href=""> link</a></p1>
</div>
And this is the css:
#border_links {
border: medium double #000000;
}
I have changed the css identifier to the id border_links because p4 refers to a paragraph of text which isn't really what you are doing.
Actually if anything it should be displayed as a list.
<ul>
<li><a href="link.html">link</a></li>
<li><a href="link.html">link</a></li>
<li><a href="link.html">link</a></li>
<li><a href="link.html">link</a></li>
</ul>
In this case you can use the style sheet to control the unordered list element (ul).
I have also changed you link syntax because it was wrong... but i think you knew that.
I hope that helps.