hmm i see, i will try this way.

Thank you Wouter.

To record in real time you need to use a musical midi keyboard or controller .... sorry, it won't record in real time using the mouse.
 
You can use Piano roll or staff view to input the notes with the mouse and that will work..... just not in real time.

I use cakewalk a A-500Pro midi controller for recording in real time. I like it's act function where you can control most of the Sonar's softsynths and plugins with the keyboards knobs and sliders. Its has a play and record button too. I would recommend that if Sonar is your main DAW. If you don't have this keyboard you still can press the "R" key on your regular " typing" keyboard when you want to record. Provided that you had armed the track for recording by clicking the record button in Sonar.

As was mentioned, you can record MIDI notes by playing a real keyboard (or MIDI controller) that's connected to Sonar or you can enter the notes manually with the mouse in the Piano Roll View.
 
I don't know of a way to actually record the soft synth in real time, but, once you have the notes in the MIDI track you can "freeze" it using the "freeze" button. This will create an actual wave file of the MIDI track. This is better than real-time-recording because if you need to go back and make changes to the MIDI track you can just unfreeze it, make the changes, and then freeze it again.
 
You can then "Bounce to Clips" which will make it more permanent.
 
Steve

If you don't have a controller? And you find that the step sequencer doesn't float your boat either? You can also use the step record function and do all the parts note by note, hit by hit and even take a coffee break mid performance, if you so desire?
 
In step record mode, I am the master (*cough* hack!) of all instruments, just ask me! Real time may prove overtly problematic...