What does this button in Sonar X2 do?

The power button turns the send on and off.
 
The "Post" button determines if the audio is sent before or after the fader.

Welcome to the forum, by the way.
 
I think it might be worth your running through the tutorials that come with Sonar.  There is a lot to learn, I'm afraid.  I will try to explain briefly, but I would also recommend watching the Videos on the Cakewalk site, and probably buying the Groove 3 or SWA X2 explained videos.  I think Karl's (fastbikerboy on here) videos would help you a lot.
 
Audio from a track in Sonar has to be routed out somehow.  In the console view (the part of Sonar that looks like a mixing desk) the signal (or sound) runs from top to bottom, just like a real desk, from the input to the output.  You can choose to "send" some of this signal elsewhere, e.g. to be processed by a reverb, whilst the rest of the signal continues to the channel's outputs.  That is what a send is.  It determines how much of the signal is sent elsewhere.
 
The fader is the slider at the bottom of the channel that increases or decreases gain (or volume) of the channel.
 
I have grossly oversimplified this, not to mention explained it badly, so I strongly suggest watching the above mentioned videos, and reading up on recording and mixing audio.
 
I can recommend some reading on the topic, if you want, but am off to bed now.
 
Good luck with your audio journey.

Yeah....What dave said. If you have Sonar Producer there's a 30 day groove 3 pass in your store account. The video on Sonar X2 is pretty awesome. There's also lots of videos on Cake TV.

Rocky

 Those buttons are part of a send thats been set up in an audio track. i.e. a send effects bus for reverb etc.. Pre is pre fader meaning the full signal will be sent to the bus without attenuation or boost from the channel fader. Post is post fader so the signal being sent to the bus will be affected by the channel fader. I hope this helps.

Rocky

bluzdog


 Those buttons are part of a send thats been set up in an audio track. i.e. a send effects bus for reverb etc.. Pre is pre fader meaning the full signal will be sent to the bus without attenuation or boost from the channel fader. Post is post fader so the signal being sent to the bus will be affected by the channel fader. I hope this helps.

Rocky

Yes. In essence, if you have the send set to "Pre", then your Fx will not be attenuated when the track fader level is reduced in volume. In other words if you reduce all your track faders to -INF, you'll still hear the full Fx volume.

Although there are applications for this, for the vast majority of cases you want it set to "Post" so that as your track fader changes volume, the Fx change with it

Thanks jb101 for recommending Groove 3 and thanks every one else, those answers helped very much :)

+1 for free 30-day Groove3 tutorial subscription!  Great timing for new users!  Welcome to the forum and world of Sonar!