We did the bounties then we went to kill these two, but where are they and how do we get to them, we are still in act one
Rakanoth and Izual are both in act 4.
Look at the portals on the map. See those little monster icons next to some of them? Those tell you which monster is in which area. Mouse over them and it will tell you which one. But if that is too much work, Izual is in Act IV top middle, Rakanoth is in Act IV lower middle.
If you’re looking for these Bosses to complete Season Journey Objectives, why not restart your game until you have them as Bounties? That way, you can knock out the Season Objectives and get some extra loot from the Resplendent Chests (Diabolic Hoard) that spawn when you kill them.
You can find many things on the Game Map just by looking and/or mousing-over location icons.
Notice the little key icon next to the Gardens of Hope 2nd Tier. Mouse-over it to see that it marks the location of Nekarat the Keywarden. There’s a different Keywarden in Act I, Act II, Act III and Act IV. (None in Act V). You start seeing them on Torment I Difficulty or higher.