LMX2322 PLL FM Transmitter 88-106MHz

hi

I am trying to design a Fm transmitter with LMX2322 PLL chip.
Kindly explain the working principle of PLL. How Phase and frequency is compared?
How N and R counters values are selected in LMX2322 for VCO at 100MHZ and Local Oscillator at 12MHz?

Regards