here's what you had to do before fighting Onyxia, the first raid boss in vanilla. nowadays to do a raid you can just press a button and wait a few minutes and
Blackwing Lair Attunement Guide - Blackhand's Command in Classic WoW - Guides - Wowhead
Classic WoW Raid Attunements Guide - a Key to Best Places in Vanilla | MMO Auctions
Classic WoW Raid Attunements Guide - a Key to Best Places in Vanilla | MMO Auctions
Vanilla WoW Gameplay - The Shiny Ones Guild 5 Man UBRS - Classic World of Warcraft - YouTube
Classic WoW - Upper Blackrock Spire Guide (UBRS)
WoW Classic/General Drakkisath UBRS last boss/Blood of the Black Dragon Champion/Onyxia Attunement - YouTube