The short answer is that you use an unlocked Rom 102 in a DN receiver (or a CS with X2 card reader); the long answer is that it is very complicated and not at all suited to someone simply looking for "free" TV.
Using cards will take about a month of internet reading, based on spending 2 to 3 hours per night online. Plus you will have to invest a couple of hundred dollars assuming you loop your first 1 or 2 cards trying to unlock them over the next few months.
There isn't one place where you can find all the info in one single read. Try googling "DSS rom cards" and join some of the sites.
It requires $$$, time, and skill, but most of all,READING. Assuming that you did a lot of reading and read MOST of the things needed to know, you can be watching TV in less than 4 hours, (NOT a joke). Is it worth it? Good question... My answer is NO. Pips thinks anything free (such as Free TV) is OK. It is in fact very expensive. And still, may end up with NO TV. DTV = $25/month DN = $20/month Pansat = sucks LOL