I already have two subs hooked up to an amp but just got another sub with an amp. How would i be able to hook up the sub and amp to work along with the other subs. I dont know how to wire like the rca's and remote
You really shouldn't mix your subs and amps like you are about to do but that's on you.
You're current amp should have an RCA output next to the RCA inputs. Use it...........If not then buy a splitter to take your single RCA output and turn it into 2. For the remote wire just tap off the wire on your first amp and run it to the new amp.