Approval workflow setup

Hi users

We were reading Peoplebook and we found that the approval in project costing is for information only, but it says that you can trigger a workflow,

but we are trying to see the work flow and anything happen.  Can you send us or explain us how to set up this?

bellow is an example of what we were trying to do.

create a project even.

the event has to status from open to approved

when we change the status from open to approved nothing happen.

Thanks in advance,

    

            Ambiorix