Welcome to stack overflow!
Give this a shot. http://social.msdn.microsoft.com/Forums/en-US/92846ccb-fad3-469a-baf7-bb153ce2d82b/simple-udp-example-code
Replace
string text_to_send = Console.ReadLine();
With some file IO bits from here. http://msdn.microsoft.com/en-us/library/db5x7c0d(v=vs.110).aspx