Your jacket - Din jakke (hankjønn/masculine) Your jacket - Jakka di (hunkjønn/feminine) Your apple - Ditt eple (intetkjønn/"neutral") Your apples - Dine epler (flertall/plural)
Din/ditt/di/dine is pretty simple to get because it's just different ways to say "your". Di can only be used with a definite noun.
Sin/si/sitt/sine is kind of different, because there's no specific translation for the words. You never really say sin+noun on it's own, because that would sound sort of odd, so I'll give examples with sentences.
Han tok på jakken sin - he put on his jacket (hankjønn/m) Hun tok på jakka si - she put on her jacket (hunkjønn/f) Det var Lisa sitt eple - it was Lisa's apple (intetkjønn) De er med vennene sine - they're with their friends (flertall/plural)
Summary: As you can see, sin/si/sitt/sine implies to something that belongs to someone in third person. Din/di/ditt/dine implies to something that belongs to someone in second person.