VB.Net Determine filename and path of file that opened my program by file association

Hi Experts.   I have associated my vb.net program with a particular file extension.   Is there a way for my program to  determine the name of the file and the path of the program that was clicked to open it?  for instance as my program opened it could show a messagebox saying - "You have opened the file C;\temp\testfile.tmp"?  Many thanks