Converting VBScript command into .NET

I am trying to convert the following VBScript command that decrypts a
file into .NET.

pgp ohw06027.elg.pgp -z778

The first parameter is pgp which is the PGP decryption software. The
second parameter ohw06027.elg.pgp is the file to be decrypted.
The third parameter -z778 is the password.

I am a little bit familiar with the shell or
System.Diagnostics.Process.St*art commands. But, I have not had any
luck with making it work with either one of these commands.

Any suggestion would be greatly appreciated.