marriage and birth certificates needed from the Ukraine

I need the marriage certificate of my grandparents Wilhelm Penner, born April, 10 1892 in Silberfeld an Maria Penner (Grunau) born October, 19 1895. They lived in Neu-Gruental, Marinpol-District, Ukraine. Does anyone know how and where to get a copy of this document?
The only thing I have is a document certifying their and their childrens, Wilhelm, Otto and ArturEvangelical-Lutheran religion. The document is signed by the Pastor of Ludwigstal W. Schlupp on September, 18 1927.
Regards from Hamburg, Germany