Setting crossovers?

Hi. I know this is probably asked a lot, but I need some help with setting my crossovers. I'm powering 2 FRC4269's in the rear deck, and 1 10" sub from a Sony XM-4060GTX amp.    I just have the 2 factory 6.5" up front, so I set the hu's high pass crossover at 75HZ. I just don't understand what 75HZ means there...anyway, I also need to figure out what to set the sub and 6x9's to, and what that value means...Thanks.

We can hear sound waves between 20 Hz and 20,000 Hz, also known as frequency. The High-pass at 75 Hz simply means that everthing above 75 Hz is allowed to pass through to the speaker. Doing this to a smaller speaker will prevent distortion and other unnatural sounds that the speaker has difficulty producing. 75 Hz is easily produced by a sub-woofer. Here's a quick reference for which speakers produce which frequencies. This is by all means not exactly accurate, but a generality. 20 - 80 Hz - bass - sub-woofer 80 - 350 Hz - mid-bass - woofer 5"-8" 350 - 1K - Mid - midrange speakers/components 1K - 5K - Mid High - same as above 5K - 20K - High - tweeters