如何在C＃.net中对字典进行排序

I need to make a frequency analysis console program using c#. It has to show the 10 most frequent letters from a textfile. I have managed to display the first 10 letters read by the program and the frequency of each character. I, however, don't know how to sort the dictionary. This is the code I have so far.I need to make a frequency analysis console pro