To listen to music with the Lecjo extension, click on the link "Get Lecjo" in the left column.
In the window that opens, click on the green tab "Add to Firefox", then validate to install the application
The installation succeeds a small red icon appears in the task bar to indicate that Lecjo is installed.
Once the installation succeeds, each time a web page contains a sound file in the multi-directional audio format, it will play automatically.