timelinefx:timelinefx.tlEffectsLibrary.GetEffect
Method GetEffect:tlEffect( name:String )
Retrieve an effect from the library Use this to get an effect from the library by passing the name of the effect you want. Example: 
local explosion:tlEffect=MyEffectsLibrary.GetEffect("explosion")

You should always use timelinefx.CopyEffect if you plan on adding the effect to a tlParticleManager

All effects and emitters are stored using a directory like path structure so to get at sub effects you can do: 

local explosion:tlEffect=MyEffectsLibrary.GetEffect("Effect/Emitter/Sub Effect/Another Emitter/A deeper sub effect")}

Note that you should always use forward slashes.