You were not clear if you wanted to print from your embedded device or from a C# application on a PC.
I suggest you have a look at the MSDN documentation here:
http://msdn.microsoft.com/en-us/library/windows/hardware/hh406260(v=vs.85).aspx[
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Windows does supply generic USB printer drivers that you can use in C#. The link above also has downloadable generic USB driver examples for you to look at. I suggest at least looking through the documentation to try and get a better understanding of USB in general. I would also suggest you have a look at
USB.org[
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I suspect you are really looking for some cut and paste code to use, you may try this link:
http://www.dreamincode.net/forums/topic/124753-usb-port-printing-through-c%23-code/[
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Good luck.