You run a Gearman server (or more likely, many of them for both
high-availability and load balancing), then have workers (using the
Gearman::Worker manpage from the Gearman module, or libraries for other
languages) register their ability to do certain functions to all of them,
and then clients (using the Gearman::Client manpage, the
Gearman::Client::Async manpage, etc) request work to be done from one of
the Gearman servers.

The servers connect them, routing function call requests to the appropriate
workers, multiplexing responses to duplicate requests as requested, etc.

More than likely, you want to use the provided the gearmand manpage wrapper
script, and not use Gearman::Server directly.