Under the main menu select extras; promotional unlocks; and select enter code. You may need to turn Server-Driven Content, located in help and options; settings.

Effect	Password
Unlock Promotional card #1	GKSNDR
Unlock Promotional card #2	DWNNDR
Unlock Promotional card #3	FTHPTH
Unlock Promotional card #4	TRCKSC
Unlock Promotional card #5	PRSTTT
Unlock Promotional card #6	RSNGSN
Unlock Promotional card #7	XBXBDZ
Unlock Promotional card #8	PXPRMD
Unlock Promotional card #9	MGCCTN