Upon your arrival, your passport will be stamped to show legal status in the U.S. The physical conditional permanent card will be mailed to you.
You receive an immigrant visa stamp on your passport, from immigration, at the airport, upon your first entry to the US.
Upon arrival, the CBP Officer will begin the processing. You will bring a packet with you and hand it over to them and they do some paperwork (it will take a while--don't be in a hurry). You will have a Visa in your passport. CBP will validate it and it will serve as proof of immigrant status for up to a year. Naturally, you will get the actual "card" long before that year is up. (UNLESS, they find out some horrible deep dark SECRET in your past!)
The packet which you hand over is sent from CBP to USCIS for creation of your permanent Administrative File (A-File) and for production of the "greencard" which will be mailed to you by trackable certified/registered mail.