"Hi
My Application creates files with the .MHM file extension.
I would like my application to be associated with this file extension so that when a MHM file is executed, my application is too, with the file path as the arguments for the main method of my application."
That's what I understood.
Grzenio has the right idea -
public void static Main(string args[])
{
...
}
but to push your application into the shell would take extra research, you'd have to look into integrating your application into the Shell (using the registry).
See here: script-to-associate-an-extension-to-a-program
EDIT: Thanks for the edit of the question Chris, trying to see things a bit wider here... Perhaps the arguments solution was all the OP needed.