A tiny bit of googling never hurts :)

https://forum.processing.org/topic/any-windows-mac-users-of-netbeans
https://forum.processing.org/topic/processing-and-netbeans

I have since found that the nice pictorial guide by shinkoru has gone. The main thing you need to include is processing core.jar this is best done by "creating a library" in the NetBeans sense. This is the path to the core.jar on linux other systems will vary (this is the minimum you need, add/create other libraries as required). See my blog for using OPENGL and other native libraries.The main difference you will find is that 2.0 for example will be seen as a double so append an f to specify a float eg 2.0f. You should explicitly declare public access such as

1.  public void setup(){