If you want to add a new document template which would be listed in the dialog box displayed by → :
Create this document template, preferably using XMLmind XML Editor. At least, make sure that the created file is valid by opening it in XXE.
Copy this file to custom/.
Let's suppose this file is called template1.xml and that you want your document template to be listed in the dialog box as "Template #1".
Add the following template configuration element to your custom .xxe file (e.g. 0docbook5.xxe):
<template name="Template #1" location="template1.xml" />