meu for masculine nouns, minha for feminine nouns. If unsure if masculine or feminine then use Google Translate to check. Eg type "the newspaper" and you will see it says "O jornal" meaning it is masculine and you would use "meu" instead of "minha".
As a rule if the noun ends in a "o" (like menino, gato, cachorro) then it is probably masculine, and if not then it is probably feminine. But there are exceptions to the rule.
(PS there is no such word as minho)