newbie seeks template info

Could somebody point me to a good primer--and I mean PRIMER--that explains how templates work in php. I'm thinking--not too clearly, I admit--about apps like Smarty and PhpLib and Pear, which I've heard so much about. I would like to know how to use templates--particularly to separate structure from content. I am a true newbie, picking up a little programming in the course of learning php. And loving it! Well-commented examples are always very helpful too--perhaps most helpful of all. Thanks beforehand for any help. Best, Daniel