Pick an army book or the core rulebook to see its rules written out in full, with the original source PDFs kept alongside for reference.
Arcane Journals hold the army-specific content — army lists, named characters, new units, magic items and missions, each kept alongside its own source PDF/scans. Warriors of Chaos is live now; more armies (Beastmen Brayherds is next, once its base Ravening Hordes units are processed) will get their own entry here as they're added.