This app is likely defunct. Facebook officially discontinued support for their legacy mobile apps on older operating systems (including S40) several years ago. If you try to launch the native app now, it will likely display a connection error or prompt you to update to a version the phone cannot handle.
To make the most of the phone's hardware while "posting," try these classic activities: 3.2MP Photography mobile facebook application for nokia 7230
Snaptu was a Java platform that modernized feature phones. Facebook acquired Snaptu in 2011 to build their Java app. The original Snaptu client is abandonware, but if you have an old .jar file, it sometimes works as a reader-only app. It is unreliable. This app is likely defunct