A reply

Dear Jack,
Hearing from you,I know you will come to Xi'an for a vacation.And I am very delighted for that. Luckily,I happen to have one-month-long holiday,so I will make you be pleasant.*

I was delighted to hear from you, and to know that you will come to Xi'an for a vacation! Luckily, I have a one-month-long holiday then, so I know I can make your stay pleasant.*
Xi'an,**the captial of Shannxi province,has numbers of famous sightseeing,sceneryand wonderful bulidings built by historical people.For example,Mount Hua,Hua Qing Pool,History museum and one of the Eight Wonders of the world and so on.

Xi'an, the captial of Shaanxi province, has many famous sights, wonderful scenery, and historical buildings. For example, there are mountains: Mount Li, Mount Zhongnan, and Mount Cuihua, to name a few. There is the Huaqing Hot Springs. There is the Shaanxi History Museum. And of course, there is the Mausoleum of Qin Shi Huang and his Terracotta Army, considered one of the Eight Wonders of the World.***
Not only can you visit many places,but also you can enjoy many kinds of snack,which juet offered in Xi'an.What's more,we will learn something from each other in a great stage.I am waiting for you soon.

Not only can we visit many places, but also we can enjoy many delicious dishes, some of which are unique to Xi'an. What's more, we will learn a lot from each other. I am waiting for you anxiously.

Yours,
Rui Mu

* This phrase seems to me a little suggestive. When a woman says to a man, "I can make you happy," I think she is implying sex. Saying "I can make your stay pleasant is not as suggestive." The problem is the "I will make you..." "I know that your stay will be pleasant is not suggestive at all." 
Now, Mr1998, I don't want to tell you what to do when you meet Jack, or what to say to him. Absolutely, you should flirt with him if you want to. I just want to help you with English. 

** Always put a space after comma, period, exclamation mark, question mark, colon, semi-colon. Never put a space before them.

*** I don't know how many people make lists like that anymore. Whether there are seven or eight wonders seems to me pretty arbitrary. Certainly, the terracotta army is world-famous, and it qualifies as a "wonder of the world".