There are 4 sets of 9 drawbars on the organ.
The two leftmost sets are for the upper manual and are engaged by the Bb and B preset keys on the far left of the upper manual.
The two rightmost sets are for the lower manual and are engaged by the Bb and B preset keys on the far left of the lower manual.
The two drawbars in the center are for the pedals.
This setup makes it easy for organists to switch rapidly from one sound setting to another.
When drawbar settings are mentioned in text, each number represents how far that specific drawbar should be pulled out. If you look at the top of the drawbars, you'll see numbers from 1-8. Zero means that drawbar should be pulled all the way in.
Example:
888800000
This means the first four drawbars in a set should be pulled all the way out and the rest should be in, which is actually a very common standard gospel setting used for basslines and right-hand.
Which of the four sets of drawbars you use is up to you and your playing style. Generally, though, organists use the upper manual for right-hand playing, and thus right-hand drawbar settings will be used, and the lower manual for running bass lines.
I hope this helps.
