Here is the demo site for DDcms. The admin is located here. The username and password are both demo. Play around as much as you like. The whole system is reset every night. Do realize this particular demo is not the latest version but is very close.

The one feature missing in the admin is user administration. There you may make add / delete / edit users. There are 2 kinds of users: admin and editor. The editor is only allowed to make changes on pages.