I'm new to cakewalk/sonar and want to learn about how to use the session drummer feature. Can someone point me to an instructional section or help area?
I just bought Sonar Professional and I'm still learning that too.
I don't have a MIDI interface, just a Scarlett 2i2.
 
Thanks.

To access the help, click in the Session Drummer UI and press the F1 key.
For more see this similar thread http://forum.cakewalk.com/FindPost/3391405

Here's a summary of steps to go through :
 
1) How to insert a soft synth (Session Drummer) with simple midi track
2) Using the Step Sequencer to program drum hits.
 
All of the above tutorial can be found at Cakewalk's Youtube channel or by others.
 
Here is a little secret that confused beginners in Step Sequencer - when you copy a Step Sequencer clip to another location, it is defaulted to 'link' pattern (to where it's copied from).  It's very common to create a basic pattern, copy it elsewhere and edit a variation of the pattern. If you do this, you will end up with 2 similar drum patterns, as they are linked. In order to prevent this, after copying a Step Sequencer clip, you will need to right-click and select Unlink Step Sequencer Clips.
 
Another way to input notes to Session Drummer is to use the Piano Roll View (PRV) where you input notes with your mouse click since you don't have a midi controller to record hits.

Another way to use Session Drummer is playing the loops loaded in the plug-in. Select a program or load a series of MIDI loops into the slots available in the UI and use a controller (in this case the bundled virtual controller) to trigger the loops recording either the MIDI notes triggering the loops or the audio played by the plug-in.

This article is about Session Drummer 2, but much of it relates to SD3. This one covers Session Drummer 3 techniques.

A thought to add...

Using the SD included clips as a starting point....

Find one clip that is close to what you're looking for...
Drag it (the pattern) to the SD MIDI track...

Now you can easily copy/paste/edit the part to your heart's delight! ;-)