Workflows and Tasks

I am interested in workflows (for informing and approvals) for our customer PO to Sales Order process.  The User Guides make it seem like Tasks and Task Sets could be a powerful tool to help me accomplish what I want, but I just can't seem to figure it out. I've done lots of searching but I can't find any useful info outside of the User Guides, which don't seem to be quite enough for me. Can anyone help me understand workflows, tasks and task sets? Is there additional documentation on these features? Thanks, Trevor