The Turn Feature Class toolset contains tools used to build and edit turn data. The tools in the toolset allow you to create new turn feature classes, convert existing ArcView or ArcInfo Workstation turn tables to turn feature classes, and maintain the integrity of existing turn features based on their geometry or an alternate ID field in cases when the reference source features are updated.
The Network Analyst tutorial exercises are a good starting point for learning ArcGIS Network Analyst. They provide data, steps, and conceptual information on how to accomplish specific goals, such as building network datasets and performing various network analyses.