How do I record mono?
 
Does anybody know how to do this? I know how to convert stereo to mono. But I don't know how to just record mono?
 
This would really help me out. I use Sonar Studio X3

Open the Inspector, and open the Track view in the Inspector.  There is both an Input and Output on your Track.  Assign the Input to either the left or right channel of you audio card.  Additionally right above the Mute button, there is a little circle-circle button which when you hover over it, will say stereo.  Click it.  It is now Mono.
 
There ya go.

Inputs in SONAR are configured as stereo pairs but need no be recorded as pairs of inputs. Recording one side of the pair creates a mono track in SONAR. Set the input of the track to a mono source, such as the left channel of a stereo pair. In addition to only recording the left channel it has the side effect of changing the track interleave mentioned above to mono.

The interleave is automatic. Sonar is smart enough to know when its inputing a mono input.