No need to apologize. Those of us who "live" on this board assume it is common knowledge. Yes, you could browse this site pretty briefly and find out all you want to know, but I understand the occasional "post from the hip", so don't sweat it. And although I'm sure jwgreen68 didn't intend to sound as scathing as he did, he's correct---just read the enclosed literature and follow the instructions. It is simple.
As jwgreen68 pointed out, it is necessary to install the cards for security reasons (on DISH's part). You will not gain more channels or features. You will, however, lose programming if you wait too long to install the cards (I think the literature says 2 weeks from receipt of the mailing).
Now, if you want to read in depth as to the purpose of the cards, then you need to scour the forums...