Create the header and save it, once you are done you'll see the Actions gray button located on the top-right side of the screen.

 Go to the Actions gray button. It will give you three different options.

 Load a Template: Clicking here will allow you to upload the items on a template previously saved. To use one of the templates, click on the Load a                  Template link and select the one that you want to use by clicking on the Select link under the Actions column.

Save as Template: To create a new template you have to add the lines to the purchase order, and once you are done click on the Save as