I need your help, please come in

hello guys:
I am a chinese student studying @london.
here I have a questiong about ZEMAX:
how can I add a 'Lambertian Diffuser' in my NSC design?
I am really in a hurry, so please answer my question if you can, it doesn't matter if you would like to use chinese.

Many thanks 2 everyone

1 right click on the object type,you will have object propeties dialog;
2 Select Coating/Scattering menu on the dialog,and then you can set Scatter Profile as Lambertain