Starting Display Tag Library

This is my very first interaction with Display Tag Library, i want to sort column. My jsp code is written below, i don't know what else to do to make it work .....

<%@ include file="../top.jsp" %>
<jsp:include page="../htmlTop.jsp" flush="true">
<jsp:param name="titleValue" value="Rahat Furnished Apartment"/>
</jsp:include>

<jsp:include page="../middle.jsp" flush="true"/>

<display:table name="requestScope.dataMap.roomType" id="roomType" class="tbl">
<display:column property="description" title="Description" sortable="true" />
<display:column property="adult" title="Adult" />
<display:column property="children" title="Children" />
</display:table>

<jsp:include page="../bottom.jsp" flush="true"/>

i have heard about comparator interface but don't know how to implement it.
Looking forward for your reply's.

Regards,

VJ