After the final submission of your application, you will receive in your e-mail (e-mail) confirmation of receipt of the application as well as an update on its reference number (see next question on the FAQs page in case you do not receive the e-mail).
Also, if you go to the "My Applications" page (under the "My Account" menu) you should be able to see your application. Once the application has been finalized, the "Application Status" column should state that "The Application has been submitted".