If you haven't accepted the membership email that you got, send me an email with the email address that you want to use on the new forum (my email is firstname.lastname@example.org). I'll be happy to give a detailed answer there. For now, I'd really recommend learning Honeybee[+] if you want to simulate light diffusing materials. It has a number of new capabilities over the old Honeybee, particularly related to light diffusing materials. Most notably, you can now run annual daylight simulations with them.