Healing requires you to heal another player who has been hit in combat (and also mending wounds/bones if they have them, when you have high enough skill). Read each skill tier (0, 30, 60 etc) carefully for details.
People told me alchemy isen't implemented yet, so I haven't even tried making potions.
The roadmap says potions and poisons are planed to come in May 2015.
https://lifeisfeudal.com/billing/roadmap.php