Overview
The class EM_HIGHSCORE inherits from EM_LOCAL_HIGHSCORE and extends it with network code, so you can send your highscore to a server and receive a global highscore from it.
Synchronize with Server
First you have to specify where the highscore will be sent to using set_url.
Then you should subscribe to several events to determine if the transfer was successful or failed. These are connection_closed_event, connection_failed_event and connection_established_event
Now you can synchronize the highscore using synchronize_with_server. The remote highscore will then be available through the attribute remote_highscore in the same way as local_highscore.
The remote highscore does also have a Web interface, which you could integrate into your game's homepage. See Server side for more info.