No problem Lucky. My advice to you would be to read almost everything over there on the left side of the screen, starting with the basics. Thats where the diagram I posted for you was from. Learn everything you can before you go ripping into your cars (or in your case trucks) electrical system, your vehicle will run much better if you do. Start with small things, your piezo siren, then maybe a set of speakers, graduate to radios and then full blown stereo and video systems. These are good places to start while you learn the basics. Only then should you attempt alarms and remote starters, there are just too many things that can go wrong if you don't know what you're doing. Your most important tool will probably be a digital multi meter (DMM). All the wrenches, screwdrivers, crimpers and cutters in the world wont do you any good if you don't know which wire you're looking for. Put your test light in the bottom of your toolbox, way in the back, and forget its there. About the only thing it's good for now is testing if that battery over there in the corner has any juice in it, and even then a DMM can do it better. Doing your own installs is only rewarding if its done right, but if it is, it's great! I don't think I will ever pay someone else to do my installs, I'd rather expand my knowledge and learn how its done myself. Having said that, I'd like to add that I respect those who professionally install security and remote start systems, it looks as easy as hooking up a stereo and speakers, but I found there was much more to it than that. My first one took me almost 8 hours to get it in and working, and Ive spent several more hours refining and adding things in the weeks since, however now I know more about how power door locks and power windows work, not to mention I've learned about the many joys of relays and what wonderful toys they are. This board and the internet in general have been instrumental in accelerating my learning curve. If you don't understand whats going on or how a particular install is supposed to go, stop and research... all the answers are here.
As for where you can get relays, I bought a few of these on ebay http:///.com/dll?ViewItem&category=75389&item=5763459947, relay , plug and wires for 6 bucks shipped for the first one, 3 bucks each after that. You can probably get them locally, maybe cheaper, but be sure to get SPDT 12 volt automotive relays at least 30AMP, 40AMP would be preferred just to be safe. You don't really need the sockets if you find they're extra, you can use female slide connectors directly on the relay, just make sure theyre on TIGHT (you dont want them to slip off and then your strobes wont work) and tape them securely to prevent shorting out. Relays can be used for endless things, lights, fans, horn honk, changing polarity, you can wire up a relay bank to keep your radio on after you shut off the ignition until you open a door, you can build a relay bank to use an auxilary channel on your alarm to turn on your radio, lights, neon or whatever without the key in the ignition, the possibilities are endless. Do some research and you'll find all kinds of stuff. GOOD LUCK!