When you first qualify for Select Plus, you should get an e-mail with a link to go to to print out your temporary select plus card. I got this e-mail the very same day that I hit the 10,000 point threshold. The temporary card is valid for two months and will allow you to access the lounge. If you never got the e-mail, I'd call Amtrak Guest Rewards right away to see if they could send it again.