Hi Sarah,
Thanks for your post.
Parallels Web Presence Builder is a CMS of its own and it's not integrated with WordPress. You probably wanted to tell us that you cannot launch WordPress within Plesk? If that's the case you will find the WordPress installation option in the "Applications" section. Since the applications tab is missing on your screenshots I assume that you or your hoster had to enable applications for your hosting subscription first.
Best regards,
Dave