Unfortunately for marriages that took place prior to July 1, 1925, there is no central file of records. You have to know the county where the license was issued to find where the record resides.
After you narrow it down to a couple of counties, there is a county contact list at www.ndhealth.gov/vital/marriage.htm
. I believe that they'll charge you for a search even if they don't find the record. Successful Searching!