You buy the box.
You flash the firmware (several choices on here- look for the mtpockets or sucmnsee's image thread).
You obtain a line.
The line is basically a file that you put onto your box that allows a remote server to decode your channels for you. It includes the ip address of the server that your box "talks" to and gets the info it needs (several times a minute) to decode your channels.
There are 2 types of lines. cline, and nline's.
Not gonna go into why, but always always get an nline of possible - its better (google why).
And, admittedly not easy to find, there IS a request area where you ask for lines, prices etc (as a guide I pay £27 for 6 months and its brilliant).
How you get that line onto your box for newbies is a pain - you need to use software like filezilla that sends files over your broadband cable from your pc via your router to the box.