Contact regional office to set up an appointment to take the exam (written and practical).
License costs $40 and is good for two years, expiring June 30th of even years (license is prorated).
If operating a self-owned truck, a milk transportation company license is required which entails a $20 fee and completion of form DY-305 (front) and DY-305 (back).
For further information, take a look at DY-304, DY-356 (front) and DY-356 (back). These may or may not apply to your specific situation.