Send an email to supervisor PR workflow

Hello guys,

I'm star to configure a PR workflow. I don't have a lot experience.

When a purchase requisition is created (me51n), I go to me54n to release the PR like a planner. So WF is initiated.

After that, an supervisor needs to release it too.

I want to send an email to warn the supervisor that he need to release the PR on your WF box.

How can I configure it?