Creating a Workflow for a record will make that Workflow accessible from any record of that record type. If the record existed before the workflow was created, then it will need to be manually attached to that Workflow.
To do this you will first select the Workflow button on a record, then Attach to Workflow and then select the Workflow that it should be attached to.
There is also a possibility that a workflow is already attached to the record type, to end the current workflow you can click on the workflow button then select end workflow.
Note: You can start and end workflows as many times as you would like, all this does is cancel any action that has not been selected and will not break anything.
When a record is attached to a Workflow, a new tab for Workflow History becomes available on the record (near the Related Items tab).
This history will log any Workflows actions taken throughout the life of the record as well as showing what nodes are currently active. This is helpful for diagnosing issues with your Workflow as well as seeing the history of how the process flowed and what dates things happened on.
Other Workflow Articles: