I would like to find my father‘s marriage certificate. I think they were married in Washington DC in or around early 1940s

I found the following:

Name Myron M Kahn
Gender Male
Age 36
Birth Date abt 1905
Marriage Date 17 Feb 1941
Marriage Place District of Columbia, USA
Spouse Anne Feldsher

You can order their marriage certificate through the DC Courts: www.dccourts.gov/.../

This sounds right, except his birth date I think was 1904.  How do I get this and what is the cost?

You can order their marriage certificate through the DC Courts: https://www.dccourts.gov/webform/marriage_certified_copy/  I think it costs $10.00, but check the website to be sure.

I filled out the form, but no one has contacted me?

Trying calling them: District of Columbia Courts (202) 879-1010