Hi, and welcome to the forums.
There isn't, unfortunately, a Time Machine Manual published by Apple. There are some 3rd-party books about Leopard, that include TM. Check Amazon or the like.
In addition to the FAQ Tip that Thomas provided a link to, you might want to review these:
Time Machine Tutorial
Time Machine 101
How to back up and restore your files
Time Machine Features
Apple - Support - Mac OSX v10.5 Leopard Time Machine
If you have trouble setting-up or using Time Machine, try the
Time Machine - Troubleshooting *User Tip* at the top of this forum. It will show you how to locate the message(s) that describe the problem, then help you fix it.