Help installing alarm

So i bought a cheapo alarm that is loud enough to wake me up at my house and to hear it when im inside my work. I have a list of the wires and where they are supposed to go from the alarm but i dont know where to put them in the car. if anyone could help that would be great.

heres the diagram from the booklet

Orange - Starter Interrupt Output (-)
Blue - Trigger (-)
Black/white - Interior light output (-)
grey - trunk release output (-)
Brown - siren output (+)
Green - Door trigger input (-)
purple - Door trigger input (+)
White - Parking light output (+)
red - +12V battery (+)
Yellow - Ignition Input
Black - battery (-)

who ever had my care before cut some wires under the dash but nothing that i know of where goes. the only reason i think they might have had an alarm was because the horn was rewired and there were two wires and when they touched my turn signles would be hazzards no matter which direction. Anyway any help with this would be great im sick of my car getting broken into.

Anyone have any ideas before i give up and pay to get it installed?

its pretty hard. i bought the car with an alarm in it but didn't have the remote. i got the remote for $40 programmed. the place i was at installed basic cheep car alarms for 100 including the alarm and labor