hello where did consecration skill go its not in spellbook or on talent tree? sorry i dont know much about the changes i dont really understand how to play my class now 
for Ret there is a talent [Consecrated Blade] that makes your [Blade of Justice] cast consecration at the targets location, once every 10 sec
There is a choice node between consecrated blade or divine hammer (I think). Both of those replace consecration. If you’ve chosen either, consecration will no longer be in the spellbook to be manually casted. Consecration damage is much lower now, anyways.
As to understanding how to play, there are multiple possible builds now, and you will need to figure out which one you prefer and relearn your rotation. Also, there are different builds for AoE, vs Single target, vs a slightly more balanced M+. That’s the bad news. The good news is the rotations are actually easier now, so once you put in the work, you will probably see a “buff” that is actually just you doing your rotation better than you did before.