how to list the children of selected node ,which is in navigation bar, in a sidebar

I need to add an additional navigation to my oracle webCenter portal project. This additional navigation should show only the children of the selected node, which is in navigation bar, in a left sidebar. How can i do this ? i try to modify list navigation but I could not. I use pageTemplate_globe.jspx. Thanks for help.

     <af:panelGroupLayout layout="vertical">

 <c:forEach var="node" varStatus="vs" items="#{navigationContext.currentModel.listModel['startNode=/, includeStartNode=false']}">
        <c:if test="${node.selected}">
            <c:set value="${node.children}" var="childNodes" scope="session"/>
        </c:if>               
</c:forEach>

<c:if test="${childNodes ne null}">
    <c:set var="childNodes" value="${navigationContext.currentModel.currentSelection.parent.children}"/>
</c:if>
<c:forEach items="#{childNodes}" var="node2">
                <af:commandImageLink id="cil3" text="#{node2.title}"
                                     actionListener="#{navigationContext.processAction}"
                                     action="pprnav"
                                     icon="#{node2.attributes[pageFlowScope.tnBean.iconKey]}"
                                     disabled="#{not node2.navigable}"
                                     inlineStyle="#{node2.onSelectedPath ? 'font-weight:bold;' : ''}">
                  <f:attribute name="node" value="#{node2}"/>
                </af:commandImageLink>
</c:forEach>

</af:panelGroupLayout>