Apply classes to your TDs, apply the appropriate widths (remember to leave one of them without a width so it assumes the remainder of the width), then apply the appropriate styles. Copy and paste the code below into an editor and view in a browser to see it function.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<style type="text/css">
<!--
td { vertical-align: top; }
.leftcolumn { background: #CCC; width: 20%; padding: 10px; }
.centercolumn { background: #999; padding: 10px; width: 15%; }
.rightcolumn { background: #666; padding: 10px; }
-->
</style>
</head>
<body>
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td class="leftcolumn">This is the left column. It is set to 20% width.</td>
<td class="centercolumn">
<p>Hi,</p>
<p>I want to wrap a text that is added to the TD. I have tried with style="word-wrap: break-word;" width="15%". But the wrap is not happening. Is it mandatory to give 100% width ? But I have got other controls to display so only 15% width available.</p>
<p>Need help.</p>
<p>TIA.</p>
</td>
<td class="rightcolumn">This is the right column, it has no width so it assumes the remainder from the 15% and 20% assumed by the others. By default, if a width is applied and no white-space declarations are made, your text will automatically wrap.</td>
</tr>
</table>
</body>
</html>