New to Arnold for 3ds Max? Below are some useful links to get you up to speed.
The MAXtoA user guide can be found here (if you spot any errors, please email firstname.lastname@example.org).
I recommend the Rendering Your First Scene page to get you started.
There are some tutorials here (more incoming in the future).
A basic material library can be found here.
The Learning Scenes are a good place for experimenting with rendering different features with Arnold.
The version of MAXtoA that ships with 3ds Max 2018 is already out of date. You can get the latest MAXtoA release here.
An introduction to Arnold 5 video for 3dsMax 2018 can be found below.
A 4-part (4 video) tutorial on the 3ds Max youtube learning channel on Arnold in MAXtoA: