Ok people, the new tutorial on my website "JK2 Mapping" is:

Doing - Force Fields

It is very interesting if you wish to create working force fields with sound and activation/deactivation actions...

The current tutorials in my website are:

Understanding
=============
JKRadiant Environment
Brushes
Textures
Entities

Doing
=====
Compiling & Packing Maps (PK3)
Skyboxes
Rain
Deforming Brushes (Hills)
Invisible Walls
Coloured Lights
Joining Rooms
Force Fields

My website address is:

http://www.geocities.com/jk2mapping/