caddy

I got a amp and sub + all the wires I need to connect RCA+blue wire into head unit but can't see where any of this would fit??? iv got a little thing with some wires on in where the rca wires would go but that had wires that come out of it and would no where to put that either?? can anyone help...

Anyone got a homemade caddy trailer? Looking at one to buy or make. Anyone selling one or hot any advice? Cheers