no clue what im doing

I have a crossfire cfa 404s amp it's been laying around for years idk some fave me it in a trade a long time ago never wanted to hook it well I looked it up turns out the old heads think it's a "beast" of a amp .. but I have no clue how to hook it up it has like a dual rca hook ups idk what to do

hi i have theses 3 subs there MTX 10ichs 1 of them is blown so i planed on replacing it and i cant find them anywhere to buy. i have no clue what I'm doing and would basically wana know if its worth buying 1 sub to replace the blown one or replace all 3. thank you for your time