I watched a few older videos and it looked pretty straight forward. I jump in and JFC my damage is just pathetic.
Given your inability to ask a meaningful question or provide any context on your gearing/talents/strat, it’s safe to assume that you just need to get good.
I haven’t done the achievements recently, but I have completed all the challenges at least once on every specialization in the game multiple expansions ago. Personally, I thought protection paladin was one of the harder tank specializations to use, just because it has fewer ways of dealing with the infernals that blow you off the edge compared to most other tank specs.
As for how much damage you do I would definitely look up the most current possible guides to find the best ways to cheese the way stat squishes work and to find the best gear, trinkets, enchantments and gems etc. Because statistic squishes are always weird, there’s usually extra powerful ways to build your character just for this specific challenge