What phrases do you recommend me learn in Japanese? (Romaji please)

日本のメキシコ人とは何か？

Nihon no Mekishiko hito to wa nani ka?

Nihon no omona dōshi. Hira ga na nomi de onegaishimasu (google traductor)??

What do you think about...learn from the sadness and the happiness, which is better?

Is this well written? "you are a great person and can contribute with a better world!!" (my question is about the verb "can"). Other way that I thought for write was: you are a great person and you can contribute with a better world!! (Is necessary repeat the pronoun "you"?)