DFS Alarm help

I have a DEH-P5200 with a DFS alarm on board, it is installed in a 1993 Chevy Beretta, i would like to install the 'alarm', i have a siren/horn, a 30 amp relay, and all the manuals  ect,  however for some reason right now none of it is making any sense,  what i have concluded so far is this:  the receiver has two wires, ones is a yellow/white wire which splices into the dome light for the door switches, the second wire is a brown, which is the alarm output.  simple so far, but here is where i get confused, the brown wire runs to the relay and connects to the where on relay? basically, how do the relay and siren interface..i may be completely off, but i work graveyards and my brain is toast. any info would be great.

you have to determine wether the alarm puts out a negative or possitive output from brain if it puts our pos you just connect it to possitive side of alarm horn or siren, and ground the other side of siren. if it is negative you have two choices you either have to give the horn constant power and join the brown wire to negative side of horn /siren or run a realy that changed polarity from negative to possitive . simple right here you go

pin 85 negative input from brain

pin 86 and 87 10 amped constant fused wire.

pin 30 output to the device ex: siren

pin 87a not used . done .