In addition to the invoice templates that are included in ProfitTrain there are many free templates that you can download. If you are in ProfitTrain go to the Help menu > Invoice Templates Gallery; or you can go directly to the page online, http://razorant.com/profittrain/invoices
Once you find an invoice template that you like click the 'Download' button to download the invoice template. That will download the invoice template to your Downloads folder. Locate the file that you have downloaded and double click it. A window will popup asking you to confirm you want to install the new theme, once you click install you will see the new invoice template as a choice in ProfitTrain.