I’m going to go out on a limb here, and guess that you haven’t worked your way through the Max/MSP tutorials. This secret as well as a plethora of others can be learned in the tutorials. I would also point you towards the "Common Max Arcana" thread which discusses some common topics.
In general what you are probably going to want to do is learn the poly~ object, and make your synth run in there. I have a couple examples showing the use of poly~, as well as some simple enveloping on my examples page: http://xfade.com/max/examples/