Yes, you need to setup the "Glass"variations of the sections you want transparent in your explorer but
there's also another section that will be the trigger for the transparency work, it's the section:
Backgrounds > Edit explorer backgrounds bitmaps > Active window (glass) and Inactive Window (Glass).
Once you set those, all transparency shows up, you just set a image with the opacity you want.
Important: after choosing the image, click in the tab on bottom called "Code Editor" and add this two lines:
Those are missing at the moment on SKS.