You really need to put some effort in your work if you want to get any results.
I'm pretty much sure you already know where to find complete description of the algorithm: http://en.wikipedia.org/wiki/Huffman_coding
]. This article includes many good Web links to implementations of the algorithm: C, Python.
This article provides implementations in 27 languages (!): http://rosettacode.org/wiki/Huffman_codes
Some of the implementation will look very similar to C#: especially Java, more or less C++, Ada (looks different but essentially very close as definitions of arithmetic operators are used). Algorithm itself is quite simple, especially when it's explained to you in such a detailed way. So, what's remaining problem? Implementation in C# using available samples? But what are you good for? I don't think anyone would be interested enough to do this work for you. The most interested person here is you. Put some effort and have the result.