ASC Tutorials

There are two tutorials available which explain ASC:

Tutorial Campaign

ASC itself features a Tutorial Campaign :

Select Game => New Game => Start New Campaign and select Tutorial Kampagne

PBP Introductory Guide

The multiplayer universe Project Battle Planet features an Introductory Guide, which explains both the ASC game and the mechanics of Project Battle Planets
http://www.battle-planet.de/pbp/guides/einsteiger.php (this guide is only available in German language)