There is no administrators manual yet. To get started managing Ariadne, take a look at the tutorials in the System Administration section. These should give you a good start on a few common tasks. In addition you should take a look at the FAQ question about performance and caching.
If you have problems or questions managing an Ariadne site, and the above links don't help, you can ask for help on the Ariadne newsgroup, mailing list or forums. You will usually get a reaction within a day.