If you are planning to move with your German spouse or your German (minor) children to Germany, you have to apply for a family reunion visa.
Also, spouses and minor children of foreigners with a German residence permit have to apply for a family reunion visa, prior to moving to Germany.
All applicants (including children) have to apply in person.
Find more information here:
Family Reunion Visa to a German Spouse
Family Reunion Visa to a non-German Spouse
Family Reunion Visa to a German Minor
Family Reunion Visa to non-German Parent(s)
Language Requirements prior to application
Visa Application Form:
National Visa Application Form