Uncharted Realms / Magic Story on the mothership (the main website). Look for stories starting with Battle for Zendikar: That's when Jace assembles the avengers gets the band back together Forms the Gatewatch and we begin our current story arc.
https://magic.wizards.com/en/content/battle-zendikar-story
Run through the sets from there: Battle for Zendikar / Oath of the Gatewatch: in which jace and the squad save? a plane and upset Ugin.
Shadows over Innistrad / Eldritch Moon: in which Jace and Lilliana investigate some spooky shenanigans, Tamiyo is there
Kaladesh / Aether Revolt: Chandra returns home, we meet Dovin, and the Gatewatch fights a revolution
Amonkhet / Hour of Devastation: Nicol Bolas Returns and the Gatewatch is not found worthy.
Ixalan / Rivals of Ixalan: Jace, cast out to Ixalan runs into Vraska and we begin to figure out the keys to Bolas' plans.
Dominaria: I don't really know what happens here.
Ravnica 3: The current set: the spot of Bolas' next invasion.
There's a character database here : https://magic.wizards.com/en/story