The more you read the better it will be explained over time. First thing to learn...20hz to 20,000 herz = frequency range used to reproduce music. That's a good starting point. Amplifier loads, i.e. 4ohm speaker vs. 2 or 8ohm speakers, aren't that important until you start system designing. I will caution, do not ever think that electrical loads are unimportant when dealing with amplifiers.

You already have a basic setup so start learning about frequency response. It's real easy with bass because it's such a dramatic difference every time you change the angle of the subs or move their position. The same thing happens in other frequency ranges too it just may not expose itself as much based on your ability to comprehend why the music sounds the way it might.