The Array object is naturally a 3D array, so you can access any point in the C2 Array by calling Array,At(x, y, z).
To import the data, you simply feed that string into Array.Load (From JSON) method.
NOTE: If you are feeding the string directly into C2 (i.e. typing it into the Json box yourself), then you need to escape all of the internal quotation marks with double quotation marks, like "".