This is the localized version "English" of FolderSync Manual. Other languages at FolderSync Manual.
The manual is related to FolderSync 2.4
1. FolderSync?
2. Quick Start Guide
3. Remember Folders
4. Preferences
Hint: If you use the sidebar, FolderSync's layout will change a bit.
There is a nice tutorial for the Version 1.3.0.0 (also works with the current versions, but some features won't be explained) here.