Helpful places to bookmark include:
The Reference Documentation for Field / AR.
A ‘Cookbook’ for Field / XR.
And a more sustained drawing example called, A Box of Rain tutorial.
Download link for MacOS Field2 (alpha.36) — Full installation instructions are here.
Download link for Win10 Field2 (alpha.35) — Full installation instructions are here.
And, of course, how to get started with the XR web server in Field.