Help with Ohms

I have been getting really into car audio lately, and am going to Mobile Dynamics West in Arizona soon, and I want to get a head start on things. I don't really understand the whole ohms thing. Amps tell you how many ohms they can handle, and how many watts they put out at that setting, and the speaker is rated at 4 ohms or 2 ohms for instance. Is the wiring, i.e. parallel or series how you change the resistance the amp experiences from the speaker? And there are dual coil subs, if each end is say at 4 ohms, do you have to hook up a 2 channel amp to power the sub? Or do you hook up a mono but wire it for different ohms? As you can see I don't know that much yet. If you have a site that would help, please post as well. Thanks.

OK here's the breakdown. You adjust the impedence that the amp experiences by the way you wire voice coils to it. If you have either 2 4 ohm single voice coil subs or one dual 4 ohm voice coil sub you can wire it in either series or parallel. In series you would achieve a 8 ohm load. If you wire in parallel you would get a 2 ohm load. If you put a lower impedence on an amp you will, generally, get more power. An exception to this rule is amps with regulated power supplies such as JL. Then it doesnt matter what impedence you put to the amp it always puts out the same power. There is still a range you have to stay within ie 1.5 ohms - 4ohms. Also, if you have a 2 channel amp and either subwoofer set up listed above you could also use a stereo set up. What that means is that instead of wiring in parellel you could wire in stereo. If you run, for example, 2 ohm stereo you will get, in theory, the same amount of power that you would in 4 ohm mono. So in the end, the amp will not affect the impedence, only the wiring of the drivers to the amp will affect the impedance. On the rockford website the have a list of diagrams to show you how to achieve different loads using different subwoofer configurations. I hope this helped some.double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

I plug this site a lot, it has good technical info in an easy-to-follow format with lots of graphics.  I spent two months studying it (I'm not a car audio professional like most of the guys here) before I installed a system.  And I refer back to it often.  It would be a good starter course for you...http://www.bcae1.com/