This LookAndFeel is design to you that you want to skin components easily with images.

Generally, you just need to replace the images and modify some related properties in SkinBuilderLAF 
class.

Suggestion, for keeping with the new version of SkinBuilderLAF, you'd better copy and rename a new file 
with SkinBuilderLAF, and create your own image older(for example assets_mine), then to test and modify 
the news copied files.