Sonar can use the on board sound chip. It wont be ideal but it will work. In Sonar you will need to goto Preferences and setup you audio device for use by Sonar. This is a matter of checking boxes and setting the sample rate and bit depth. I would start with 44.1 kHz and 24 bits. Once that is done its simple to record using Sonar.
In a new project with an audio track just click the record arm button on that track and make sure its input is your sound chip's mic input. (All this is in the manual.) Than click the record button on the transport. You should hear a click of the metronome and the Now Time indicator should be moving. Speak into the mic or play your instrument. You should see audio being recorded on that track. After that hit stop and un-arm the track. Play it back by clicking play.