Customizing liferay hook custom fields

Customizing liferay hook custom fields

I need to add a Custom Field to Site create page, i went to Portal >
Custom Fields > Site and added a custom field named "licence".
I followed this tutorial
http://www.liferay.com/pt/community/wiki/-/wiki/Main/Custom+Fields+and+JSP+Hooks
I'm trying to access this field in details.jsp page. It's located at of
tomcat-7.0.27\webapps\ROOT\html\portlet\sites_admin\site i tryed to do
this:
<liferay-ui:custom-attribute
label="Licence"
className="<%= Site.class.getName() %>"
classPK="<%= 0 %>"
editable="<%= true %>"
name="licence"
/>
but it's wrong. How can I access the Site custom field that i added??
Thanks!!