Dear Li Ming,
I am more than happy to hear from you,in your letter ,I known that you have been accepted into Si Chuan university which is the best one in si chuan province.Of course,the rapid development of higner education makes huge contribution to us and offer us more chances to receive higner education.
    However,there are a wealth of differences between college life and the life of high school .To be first ,you enjoy more free time than high school .You can take advantage of it to arrange for your life and study .Beside s, each university contains a weath of different communities[社团]that are runned by students .Especially, the university also lies a lot of huge business opportunities to be seized by some students who are specialized in it .
      In my eyes ,you should make a good arrangement so as to succeed in your college life .You had better set a goal as soon as possible.That is to say : you should know what is your heart desires in the days ahead. Then ,you can make use of your free time to sign up for different optional course according to your needs .It is worth our attention that society is a value resource , from which we can gain a weath of useful social knowledge.
      Simply put, I wish you can enjoy a good and successful college life.
                                                                                                                                          Yours,
                                                                                                                                                  Zhengrong
  请帮我批改一下嘛！谢谢！我一定会更努力的！

I known that you have been accepted into Si Chuan university /I know that you have been accepted into Si Chuan university 如果用过去时I knew that you had been accepted into Si Chuan university
higner education / higher education

好的，谢谢哈