Re Paired card without reading! Any way of getting back on?

hi m8 I cant seem to download oscam may be because i've just joined anyway i'll cross that bridge when I come to it,what is the best oscam for a dm500s and I gather I'll have to FTP it to the box how do I do that ? or I should say where do I download it to on the receiver, even if you could direct me to the correct post thanks