Once you have downloaded the module, unpack it into the (sitedir)/advancedworkflow directory (it will complain if it isn't!).
Add the WorkflowApplicable extension to the classes you want managed by workflow. This is likely to be SiteTree objects, so add in
For SilverStripe 3, you won't need do do any configuration as the module contains the modifications to the _config.php file. Check the (sitedir)/advancedworkflow/_config.php file for the "WorkflowApplicable" line before editing your main _config.php file. If the "WorkflowApplicable" line is in both _config.php files SilverStripe will throw an error.
Run dev/build by opening http://(yoursite)/dev/build in your browser to get everything initialised. You may need to run dev/build more than once to get everything working (keep running it until there are no more green lines in the output of the page).
Once you log into the backend of the CMS, you'll see a "Workflows" section menu at the top of the screen. If you navigate to a page object, you should now see a "Workflow" tab along the top list of page tabs next to Content, Behaviour etc; if you look at the tab, you'll see an "Applied Workflow" and an "Effective Workflow" field. For now this will just be set to "Inherit from Parent", with no other options in the list.
Before creating a workflow, it's worth reviewing the terminology being used
We're going to create a simple two step workflow that
Before starting, make sure that the "Editors" and "Managers" groups exist in the system
Along the top section menus, click the "Workflows" option. We'll now create our workflow definition; first, we'll define all the actions, then join them up with transitions.
Okay, now we need to join these all up so that users can make appropriate choices!