Find & replace hex values in a .dll file using C#

Hello everybody :)

First of all, I have to say that I'm not professional in C#...

a little algorithm may say what I need better:

1.Start;

2.Open the file "C:\avkon.dll";

3.Find hex value for example 00 28 5B D0 00 20;

4.Replace it with 00 28 c0 46 00 20;

5.Save the file;

6.Done;

Thanks a lot :)