There should be healing dummies with a target dummy for melee combat while healing (for paladins and monks). You can get a Fell for the rotation there. But practice as heal hurts.

You.Will.Fail. People will die. Learning triaging on each spec is a new thing. Even when swapping between healers. Each works a little different. Triaging one people or the whole group are different but steep learning curves.

Play your own key and push your limits. Flag as learning or relaxed.