Ok lets say you got a nice reese going with 2 or more detuned saw waves and a nice melody. Now route them all to filter 1 (push the "bus" all the way up on all osc's). Set filter type to LP12db/oct for example.
Now in the mod matrix, set source as "EG1", which is Envelope Generator 1. Set the range to full and curve to B-LIN-. The destination will be Filter 1 cutoff.
Now in the envelope generators menu go to 1, which is the EG1 you just routed to the cutoff. Push the amount all the way up.
Now when you start playing with the settings of the envelope you'll hear the results.
DEL is the amount of time it takes before the envelope starts, set that t 0 for now.
The basics of the envelope are:
A is Attack, means the curve how the cutoff will go up in this case. You can set the strength of the curve by clicking on the curve icon.
D is decay, after the attack has gone up this will measure the time and slope to the next phase, which is
S for Sustain, is how the value (cutoff in this case) will be for the sustained part of the note, eg. when you still have the note pressed down.
R is Release, meaning how the value will act when you release the note.
You'll best get them by testing tho, and Z3TA has these other cryptical values about slopes too. Just experiment and youll get the idea.