I am a fail as a healer, what dps class should I try instead?

[Urthdigger]

Keep healing. Every class has its difficult parts, and if you're thinking "Oh I want to play DPS because nobody will care if I'm bad" please don't be that person. Just tell people in duties that you're new, learning, and looking for advice. See if people on the novice network are willing to go through dungeons with you and help coach you. You can improve, and you'll find that healing is both very appreciated, and very easy.

[Aelitalily]

As has already been said 1. dont give up!
BUT if you are really not enjoying it group content I can suggest SMN or SAM as options depending if you want a caster or a melee dps.
I main WHM but I do enjoy those 2 DPS classes in particular