http://www.auswaertiges-amt.de/DE/AusbildungKarriere/IO/Organisationen/VereinteNationen_node.html#doc345060bodyText3
Opportunities in the U.N. (in German)
Both the U.S. DOS and the German Foreign Ministry (AA) try to coordinate fairly closely with the U.N., so though this information is geared to Germans it is relevant to U.S. people too, since the U.N. is an international organization.
translate.google.com
dict.leo.org
in case you have language difficulties.