There is a article at linux and main about liquid .
http://www.linuxandmain.com/news/liquid.html
I used it to setup the theme after installing it. Basically it says.
choose
Look & Feel > Colors > Liquid
then
Look & Feel > Styles > High Performance Liquid
then
Look & Feel > Window Decoration > High Performance Liquid
There are three themes in the Window Decoration dialog to try.