Amos
I did a quick search and the motor is a 1.8 degree stepper motor (200 steps/rev) This is quite normal.
Now you need to know something of the stepper driver. Look for a model number. 16 micro steps is common with the Chinese drives. Sometimes the number of microsteps can be set with dip switches.
Count the teeth on both the pulleys. This is the simplest way to get the reduction ratio. Say the small one was 12 teeth and the large 72 teeth - 72/12 = 6 to 1 reduction
In the above example I said mine was 10 to 1. Actually I have 14 tooth and 120 tooth. 120/14 = 8.571428571 to 1 reduction. Not such a nice round number but perfectly OK.
Greolt