Once the Project Amendment has been setup, go to any approved job, hover over the SUMMARY ACTIONS button and select Project Amendments.
From here, select the Create New Request button.
In the modal that pops up, you will be able to select the amendment type as well as any of the fields for that amendment type. You can also add a comment if required.
Once you click submit, the amendment request will be sent to the approver. If you have setup auto-approve, then the amendment will be made there and then.