To become a healer in Puddleby: you must convince Master Hekus you are worthy by collecting three items that are given to you by people scattered around town.

Once you are a healer, you will be able to train with several more trainers specific to healers. You will also have access to a library and a testing area where you can prove you've advanced far enough to become a second circle healer.

The Trainers:
Eva: Eva is an all round trainer. She gives you a little bit of everything, including all the other first circle healers plus Horus and Awaria.
Faustus: Faustus trains you to heal others faster. This has the side affect of draining your health and spirit faster.
Sespus: Sespus increases your total spirit. This means you wont be drained so fast when healing others. Also, you'll be able to gain health faster when slightly injured.
Respia: Respia improves the rate that you regain your spirit at.
Higgrus: Higgrus increases your total health. He does not affect your defence.

The Test:
To advance beyond the first circle you have to pass a test. The test is to raise Glory while you're being attacked by several creatures. The test to advance to the second circle consists of 2 Giant Vermine and 2 Large Vermine.

The second circle:

The trainers:
Sylpha: With enough training with Sylpha and a Sylphstone ring, you can heal yourself without holding a moonstone. 30, is needed, I think. The ring costs 250 coins.
Horus: Horus training helps you raise people who are badly fallen.
Awaria: With Awaria training, you'll gain more health when you heal yourself.

The test:
Three Night Wendecka and one Greymyr will be trying to keep you from raising Glory this time.

The third circle:

The trainers:
Hardia: Similar to Bodrus. Trains in strength all round. Capped at 300.
Proximus: Improves your ability to use a Caduceus or Mercurial staff.