I assume you mean outputs.
How will they be powered?

1) Yes I meant output, excuse me.
2) I don't know, the speakers now only have a cable that is connecting them to the subwoofer. Can the plate amplifier give power to them?

 

I would just look for a complete powered sub at thrift stores. There's piles of them, usually under $30. Or fork out a bit/lot more money for a used AVR complete with speakers.

 

the speakers now only have a cable that is connecting them to the subwoofer. Can the plate amplifier give power to them?

No, the plate amplifier has just one amp to power the subwoofer speaker.
The side speakers need their own, separate dual audio amplifier.
Or you need an amp that has three powered outputs, one for the sub and two for the side speakers,

 

No, the plate amplifier has just one amp to power the subwoofer speaker.
The side speakers need their own, separate dual audio amplifier.
Or you need an amp that has three powered outputs, one for the sub and two for the side speakers,

OK, what if I use this?