Select DrumMachine in the drop down menu from a blue Instrument channel.
After selecting DrumMachine, up pops the DrumMachine unit, where you can adjust the each of the 8, drum sounds in the kit.
Double click on the instrument track to create a new note clip.
You can audition the sounds on the vertical keyboard. The DrumMachine starts at C3 with the bass drum and moves up chromatically (step by step- white to black keys).
The drum kit note range is within the red box on the keyboard pictured above.
If you want to continue to work on the beat beyond one bar, extend the window to the right and click on the black area and the grey grid will extend.
On the upper right hand corner of the Edit Not Region box, you can open the Quantize drop down menu and select a setting that will affect the feel and swing of the beat. It will only affect selected notes, and even though you have quantized some notes you can easily change their position later.
You can change the volume(velocity) of individual notes by selecting the velocity tool on the top of the Edit Not Region window. Hold the cursor over a note or set of notes, and while clicking on the cursor drag up to increase the volume (color becomes red) or down to lower the volume (color becomes green).