School Districts across the country are different in structure. I started school in Washington State at the Mill Creek District #18. It was the 18th school area to establish itself as a school district. It was a one room school dating back generations. When I went to the Junior High in Colville, it was District 115.
It appears Nebraska had a different system through the years. In 2005, the Omaha Public Schools basically consolidated 25 schools into one District. The Millard Public Schools was one:http://en.wikipedia.org/wiki/Omaha_Public_Schools
The Millard School District, Millard, NE: http://en.wikipedia.org/wiki/Millard_Public_Schools
Annexed by the City of Omaha in 1971
I'd suggest contact of the Millard School District:http://www.trulia.com/school-district/NE-Douglas_County/Mill...
Ask if they have a person that is a "historian" or has knowledge of who within the State Public School Administration would have such information, pictures, etc. Since you only had the District number versus a school name, you might have to first establish the name of the school.
The Omaha Superintendent's office:http://www.ops.org/district/CENTRALOFFICES/OfficeoftheSuperi...
Also the State Board of Education:http://www.education.ne.gov/documents/AskNDE.html
There are probably other social networks that might help:
Facebook: The Millard High School alumni:https://www.facebook.com/#!/groups/MillardHighAlumni/?fref=t...
The search for actual classmates... Class reunions? www.zabasearch.com
might help find some of the unique names. Based on your post, you were about the class of 1965/66? There are probably a number of classmates...and once found, that expands greatly.