Alfresco: overview page on the Wiki; has pointers to useful looking guides, including Advanced Workflows - rolling your own workflow .
Alfresco uses jBoss' business process module(jBPM).
JBOSS
jBPM jump page : docs, downloads, fora, etc.
jBoss has a process design GUI available as an Eclipse plugin.
GUI tutorial: Getting started: how to make your first process definition. , all the way through testing.. Downloads for tutorial: jBPM downloads, jBPM starter kit is supposed to have everything needed for the tutorial. Installation instructions have drifted from products e.g.[ a jboss blog:|http://blogs.jboss.com/blog/kaers/] :
AF also supplies a Getting Started bundle. Use this one instead; the readme.txt gives steps to point Eclipse to the jBPM runtime .