I just recently got Sonar X1 LE and can't seem to figure out how to record drum tracks from the SI Drum Kit soft synth - or even drums at all. It won't work (more likely I'm not doing it right), and I was wondering if it's because I need to buy the SI Drum Kit package for it since the one I have just came with the software. It's frustrating me because I want to get to work! Please reply.

Are you trying to record them while clicking on them with the cursor and mouse?
 
If so, you cannot record them that way.  You can trigger the drum samples with a midi device like a keyboard (and record them) or you can program them using Piano Roll View or the Step Sequencer.

I was trying to record them like you do for audio as in clicking the record button and then pressing r on the keyboard. How do you do it the way you're suggesting then? I read something else that said you assign a midi track to the drum kit and I tried that but with no success.

Have you spent a few hours just studying the help files/manual?
After inserting SI-drums you record MIDI on the MIDI track that is automatically created (or draw it the Piano Roll view). This MIDI then triggers the drum sounds. That's the way all soft synths work.
Or you drag the MIDI-loops from SI-drums on the MIDI-track and edit the loops to your liking in Piano Roll, if they're not exactly like you want.

Ah I see..thanks for the help.