"mein" means "my" for masculine and neuter singular nouns in the nominative case. e.g; "Hier ist mein Hund" ("Here is my dog.") "meine" means "my" for feminine and plural nouns in the nominative and accusative cases, and also means "mine". e.g; "Wo ist meine Katze?" ("Where is my cat?") AND "Das Vogel ist meine." ("That bird is mine."). -by the way "Deutsch" (always with a capital letter) means "German" (the language of Germany) IN GERMAN. In English, you should always refer to it as German, only call it "Deutsch" when you're actually speaking German.

Masculine, feminine neuter, accusative, plurals, etc, etc. You HAVE TO study these things. Google a decent page.