This guide shows how to create a simple JavaFX desktop application that stores data in Couchbase Lite and synchronizes it with a Sync Gateway instance. The application uses the Couchbase Java SDK, JavaFX, and Maven to build a desktop application that can save and load Todo objects stored in Couchbase Lite. The application includes a UI with input fields for title and description, a list of saved Todo objects, and a save button. Data synchronization is achieved using bi-directional replication between the desktop application and Sync Gateway instance. The guide covers setting up the project, creating the Couchbase singleton class, designing the desktop application, synchronizing data between desktop and server, and running the application with Maven and Sync Gateway.