Here is a link to a paper about this technique by the inventor, if you want it straight from the horses mouth!!
https://www.ctahr.hawaii.edu/hawaii/downloads/Three_Non-circulating_Hydroponic_Methods_for_Growing_lettuce.pdf
Also, here is a great resource with lots of pictures and more instructions as well.
http://www.fao.org/3/a-az029e.pdf
This link also has some nice DIY instructions for building a system:
https://www.oysoco.com/hydroponics/10-hydroponics/44-the-kratky-method
I hope these resources are helpful!
