how to create new application and use XQuery with Orbeon

Hi!

  I was assailed by XQuery for a long time, because it always has no response to me. I have already tried to search the solution, but don't get the point. Could you please help to solve this problem? thanks a lot!

Below is my code(refer to Orbeon) in one file:

<xforms:model id="topic">

            <xforms:action ev:event="xforms-ready">
               
                <xforms:insert nodeset="instance('list-documents-query')"
                               origin="instance('god')"/>
               
                <xforms:send submission="list-documents-submission"/>
               
            </xforms:action>

           <xforms:instance id="god">
                <exist:query>
    <exist:text>
        xquery version "1.0";
                        let $collection-name := '/orbeon/exist/rest/db/orbeon/xforms-bookcast/www.xml'
                     return
                   <document>
                                {string($collection-name//topic[1]/baseName/baseNameString)}
                   </document>
                </exist:text>
                </exist:query>
          </xforms:instance>

          <xforms:instance id="list-documents-query">
        <exist:query/>
     </xforms:instance>

          <xforms:instance id="documents-instance">
                <document/>
          </xforms:instance>

     <xforms:submission id="list-documents-submission" ref="instance('god')"
               method="post" action="/orbeon/exist/rest/db/orbeon/xforms-bookcast/?search"
               replace="instance" xxforms:instance="documents-instance" f:url-type="resource" xxforms:readonly="true"/>

</xforms:model>

          <xforms:output value="instance('documents-instance')/documents/document"/>