One possible version
Dear Sir or Madam,
I am writing this letter to apply for a positon in the exchange programme, Being a social person, I enjoy meeting people and learning about a different culture, I am pround of my country and know a lot about its history and culture and I would love to tell people about it ,Now I am studying at a boarding school here in China, so I am used to living away from my family. I may be homesick but I can quickly fit in.Besides ,I think new experiences are good for developing one’s character and the programme would be a wonderful opportunity to learn and improve oneself.
I hope I can have this wonderful chance
Best regards
Li Hua
略