How do I run powershell script in Workflow which will fetch users considered in the stage step and update certain attribute after migration

Hi,

How do I run powershell script in Workflow which will fetch users considered in the stage step and update certain attribute after migration. As of now I am not getting sufficient material to comprehend if it is possible via workflow.It just says normal powershell step but not sure how it will act only on those users which were considered in the workflow and wont execute on all users in general.