This is true for every aspect of WoW, and life in general to be honest.12/08/2018 00:10Posted by Jaliscobeing "bad" is part of the process -- it's the point, where everyone starts.
It's incredibly rare to try something and be instantly good at it, having the guts and determination to keep trying is what makes the whole difference though.
If you want some pointers, IcyVeins and Wowhead have amazing guides for all classes and specs put together by players who know and play the classes.
I regularly use these guides myself at home when I'm trying a new class or spec (my main has been the same spec since mid-Classic when a buddy of mine taught me the ways of the old Talent Trees).
Keep at it though, and don't ever be afraid to make mistakes, that's how we learn :)