Dear Jane,
How about your summer holidays?I am travelling in Zhangjiajie on Changsha with my family.There is beautiful weather every day.I am taking photos which let me show them to you after I come back.My parents are hiking now.See you soon.
in Zhangjiajie on Changsha
Zhangjiajie,Changsha 这种用法是比较正式的,例如在报纸上的文章,日常英语（即是口语）会用介词将两个地方连起来.
I……with my family.
英文裏不会用 I and my family / my family and I,只会将I（我）放最前,和我在一起的其他人用 with XXX 连起来放最後.
beautiful weather
地道英语,大晴天的意思.连著 every day 便是『（那里）每天都是大晴天.』
hiking
地道英语,登山或是爬山的意思,英文裏climbing指的是技术攀登,也就是要用绳索辅助的那种攀岩式的爬山方法才能称得上是 mountain climbing,像我们一般的爬山只能说hiking或者hiking in mountain.