My 485 has been approved. What is next?

My friend told me when I recieve 485 welcome notice, it will tell me to make appointment with local CIS office and they are going to put a stamp on my passport as \'temporary green card\', then they will mail me formal green card. And \'putting this stamp on passport\' is a necessary step before I get green card.
My friend got his GC on 2004.
I have just received my 485 approval notice in mail. When I read it I didn\'t find the information asking me to make an appointment with local CIS office. It said the green card will be mailed to me in 3 weeks.
Just wonder what is going on? Thanks.