i do not know how to proceed.

Henry HEDRICH
Birth 17 July 1848 in Hesse Darmstadt germany
Death about 1931 in Baltimore City, Baltimore, Maryland

only likely emigrant record for him.
5 May 1862
Age: 13
baltimore Maryland, USA
H. Hetterich from hessia on Adolphine sailed from bremen.

he married
ALENA M KLANKE
Birth 22 Feb. 1852 in Maryland
Death 1935 in baltimore Maryland, USA

her parents are:
John P KLANKA
Birth abt 1825 in Hesse-Kassel
Death 1935 in Baltimore, Maryland, USA
and
Sophia K BRUER
Birth about 1823 in Hesse Darmstadt
her mother was:
Elisabeth Bruer
Birth about 1802 in Hesse Darmstadt

ALENA HEDRICH was born in maryland, her dad in hesse-cassel and mother in hesse-darmstadt, she read german and spoke english with a strong accent. german was the 1st language in the household, her girls read german, they attended a german speaking lutheran church in baltimore.

so i need to access 1800-1850 hesse records.
is there a good faq to read on the topic?