I like this guide for tanking:

https://www.youtube.com/watch?v=bCbt67TsqmY

It's slightly dated but not much has changed between patches (a lot will change with the expac though). Generally solid, IMO.

Here is a white mage guide that looks solid (although I haven't reviewed it in depth, I mostly learned healing by doing).

Note that both of these guides are rather endgame oriented. Low level healing should be pretty easy to just figure out as you go.