Go to Purchase Orders > Add PO and select the Standalone PO mode.

 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 Template option, click on the New Template link, name it and save it.