The basics of it would be using Two (or Three) Pass Filters (High, Low, Band-Pass for mid range), followed by an amp or control stage, then summed back together at the output.
Some circuits are simple, like the Baxandall, which only uses a op amp to sum the signals back together, while others use an op amp at each frequency, and sum it back with a fourth.
As for your question
From my understanding, an Active High Pass filter is a treble booster, while an active low pass filter is a bass booster? Is the basics of it that?, that is not correct.
A (active or passive) Pass filter only does what it says. It Passes and Filters a signal. A High Pass filter lets High Frequencies through while blocking the rest. A Low Pass does the same for Low Frequencies. And a Band Pass is simply a combination of the two, allowing a mid range of frequencies through. You still need a control or amp stage to boost or cut down those frequencies, and a summing stage to put them back together.