[RWP] Increase / decrease an FX in a time selection

[ROBIN Alexis]

Hello all,

AA simple question. In an introduction, I want to use an FX with a fade 
out style. I mean, the effect should dicrease his effect little by 
little to acomplish a sweet transition with the following of the song.

In clear, is it possible to specify a starting value, an ending value 
and the decrease duration of this FX?

Thank you,

Alexis ROBIN