You can get template files for developing  processing here .  The easiest way of installing these files is to copy them to the .netbeans folder, which you will find in your home directory. There will be  a subdirectory 7.2, a further sub-directory config. If there isn't a Templates folder in that directory, then create it, and similarly create a subdirectory Classes. Copy the three java template files into this folder.  If .nbattrs doesn't exist copy this  one there  or edit the existing file appropriately. Install the processing.png icon in the Templates folder.