The amplifier's RCA ports are for input - your music has to come from somewhere, right? It's not like an iPod/MiniDisc or Discman with its own headphone output.
Next to the RCA ports are speaker cable connectors. There are just too many types of speaker terminals, like the cheapo pins on the cheaper Dayton T-amp (the Sonic Impact rebadge). It's the same kind of speaker terminal on most standard Hi-Fi amplifiers, and probably the same as on the passive speakers. These binding posts aren't universal though - some have a hole in the rear so you poke the bare copper or banana plug-terminated speaker cable in there and then lock it, or the barrel has a hole in the middle and you poke the bare copper or spade-terminated speaker cables into that and screw the lock to keep them in place.
Whatever you do, DO NOT:
1) attach the cables while the amp is plugged in/switched on
2) cross the - and + of each or even both terminals - either buy cables that are pre-terminated with bananas or spades (check which work with the Dayton) or make sure you know what you're doing with bare copper (ie, strip the shielding, twist the exposed copper, insert and secure into each terminal without undoing the twisting or leaving any copper sticking out where itcan touch the other terminals, etc).
Also check for proper polarity - make sure R-red on the amp is connected to the red terminal on the right speaker, and so on. Some speaker cables come with some way of telling which is which, ie, one run of a combined pair is of a different color (black and white for Belden's 12ga) or a strip of some color runs through one (grey on Belden's 16ga).