To execute a program in python you must first call the python executable and pass it as an argument the program you want to run, so in your case it would be something like this:
Shell("python path\programa.py arg1 arg2")
For this to work, the python executable must be in the environment variable
PATH so that the system can find it.
Anyway, instead of
Shell I would recommend using
Process which is more powerful and flexible. In your case, it would be something like this:
Dim ejecutable As String = "pyton.exe" //aqui puedes poner la ruta a python.exe si no está
//en la variable de entorno PATH
Dim psi As New ProcessStartInfo(ejecutable)
psi.WorkingDirectory = IO.Path.GetDirectoryName(path) //Cambias el directorio activo a tu path
psi.Arguments ="programa.py arg1 arg2"