One possible version：

Dear Mike

I’m very glad to tell you something about Beijing and Shanghai.

Beijing is the capital city of China. The population of Beijing is about 20 million. It covers about 16,410 square kilometres. There are lots of places of interest in Beijing, such as the Great Wall and the Summer Palace.

Shanghai is the biggest city in China. It is a modern city. There’re about 23 million people in Shanghai. It covers about 6,340 square kilometres. The World Expo was held in Shanghai in 2010. Have you ever heard of it?

I hope you can visit China soon.

Yours

Wang Hong

翻译

一个可能的版本：

亲爱的迈克：

我很高兴告诉你一些关于北京和上海的事情。

北京是中国的首都。北京的人口大约有2000万。面积约16410平方公里。北京有很多名胜古迹，比如长城和颐和园。

上海是中国最大的城市。这是一座现代化的城市。上海大约有2300万人口。面积约6340平方公里。2010年世博会在上海举行。你听说过吗？

我希望你能很快访问中国。

你的

王红