Do you mean local vars or private vars?
local variables are created the same way global variables are. If you drag a variable to be subevent, it becomes a local variable... and vice versa.
The only difference is that Global variables are always Static, but you can make local vars static too. Static means it remembers what the value of the variable is after each tick.
And then private variables are ones which are held by an object or a family.. so they are not created on the event sheet.
The manual will explain these things better than me though.. so it's better to read about them there. Is there anything in particular about the .capx that you don't understand?
So do you want a particle effect to be created and destroyed for each fan when toggled active? Because you can do the exact same as what i've done for the 'fanarea' object. If you replace every occurence of 'fanarea' with the particles equivalent, it'll probably help you understand the .capx better. And then you can modify it to have both the fanarea and the particles together.
Other people may choose to do this in other ways though, for example you could have the particles and fanarea both in a container for the fan.. that means they will always exist in the game, not be created and destroyed unless the fan is. In this case you have to some more toggles -set the particles active/inactive, and only apply the force when the fan is active also.