Your homework assignment tonight is to read chapters 1 through 5 of this post:
Although your alarm is from a different manufacturer, you may have similar questions that are in this post.
I install starters/alarms in this way:
1. Remove any unused wires from the product'* harnesses. For instance, there is usually 2 door triggers, positive and negative. Since your car has a negative door trigger you can just eliminate the positive one. This leaves you with less of a nest of wires.
2. Locate the target wires in the vehicle. You'll be working under the steering column and the left kick panel mostly so test and verify all of the target vehicle wires. Mark them if you have to. Plan ahead for additional relays for VATS, trunk pop, etc.
3. Make the connections. Some say solder, I say "tap and wrap". Your choice.
4. Test the system. All functions. Adjust and correct as necessary
5. Put back together and enjoy