Voice Editing/subliminal recording help

I have currently been playing around with the audacity program, i like it very much. But i am having some difficulties trying to figure out who to edit my voice recording to be a subliminal message. I go to the voice equalizer and i understand that i need to do a low pass filter at 15000hz range. But how do i do so.

In Audacity 1.3.14 there is a low-pass filter in the Effect menu (bottom half of the menu).

what is subliminal recording and what does low-pass filter do?

See: Missing features - Audacity Support

WC

See: http://bit.ly/xcAcSM

the sites have too complicated english T___T