How to use

[red phoenix]

I want to use <s:tree id="..." rootNode="..." nodeIdProperty="..."
nodeTitleProperty="..." childCollectionProperty="..." />,I read
treeExampleDynamic.jsp of struts2 document,like follows:
<script>
function treeNodeSelected(nodeId) {
dojo.io.bind({
   url: "<s:url value='/tags/ui/ajax/dynamicTreeSelectAction.action'
/>?nodeId="+nodeId,
   load: function(type, data, evt) {
   var displayDiv = dojo.byId("displayId");
   displayDiv.innerHTML = data;
 },
mimeType: "text/html"
});
};

dojo.event.topic.subscribe("treeSelected", this, "treeNodeSelected");
</script>
<div style="float:left; margin-right: 50px;">
<s:tree
    theme="ajax"
    rootNode="%{treeRootNode}"
   childCollectionProperty="children"
   nodeIdProperty="id"
   nodeTitleProperty="name"
   treeSelectedTopic="treeSelected">
</s:tree>
</div>

I don't know what meaning of  dojo? I don't use the object dojo before! And
I don't know how to use it.Anybody can tell how to use it? I want to make a
dynamic tree,and I can add,modify and delete any node of the dynamic
tree,how to realize it? Is there a source code for me?

Thanks in advance!
Best regards,
phoenix