Here are some Sporth learning resources (most of them by Paul Batchelor):

• The interactive cookbook is a tutorial where you can run all the example code online (it's based on the original cookbook).
• The examples demonstate a variety of Sporth ugens. Note: those that rely on external files will not work in AudioMasher.
• The Soundpipe modules reference goes into more detail on the underlying function powering each Sporth ugen.
• The AudioMasher collection can certainly be used as learning material.

And some information about AudioMasher:

• Frequently Asked Questions
• Source on Github