Movie is warcraft 1,
Prob best to either read the books or play/watch warcraft 1,2 and especially 3.
Or go look up nobbel87 he does good lore videos.
Watch “Story of Classic World of Warcraft” on YouTube
Story of Classic World of Warcraft: https://www.youtube.com/playlist?list=PLV3Yvqnl3FYdyi9i55IOCb2oJYUkiNFNw