Discipline Priests & Atonement

[Sabra]

I am having real difficulty finding information on how Atonement actually works for healing groups. I don't know if I have to hit each party member with certain spells in order for them to benefit from Atonement or it my own individual damage is enough to activate Atonement on all party members.

I am also seeking macros that will help me with healing groups in this spec.

Clueless as usual and I certainly don't want my groups to have to put up with my on-the-job learning curve.

Kan, any insights?