The best way to get started with the GeoEvent Extension is to work through the Introduction to GeoEvent Extension tutorial. This tutorial includes step-by-step exercises that introduce the ArcGIS GeoEvent Manager, creating Input Connectors and Output Connectors, and creating and publishing GeoEvent Services. Also included are exercises that introduce how to configure and integrate different filters and processors into GeoEvent Services.
The Introduction to GeoEvent Extension tutorial, as well as additional tutorials and connectors for a variety of third-party devices and data streams, can be found on the ArcGIS GeoEvent Gallery.