There are 2 ways to get a node in a workflow, you can either use the run action wizard or add the node to a space that has a rule defined that will apply the workflow.
On the details page from the more actions menu choose "Run Action", choose simple workflow from the list and sepcify the options.
Alternatively, create a rule for a space and select simple workflow as the action. Then put some content into that space and look at the details. The document details should then show you the workflow details.
