How a rgb led panel ( 16x32) works?
I'm going to basically just excerpt from Adafruit's learning page on this subject.

Keep in mind that these displays are normally designed to be driven by FPGAs or other high speed processors; they do not have built in PWM control of any kind. Instead, you're supposed to redraw the screen over and over to 'manually' PWM the whole thing. On a 16 MHz Arduino, we managed to squeeze 12-bit color (4096 colors) but this display would really shine if driven by an FPGA, CPLD, Propeller, XMOS or other high speed multi-proc essor controller.

... and ...

On most Arduino-compatible boards, you'll need 12 digital pins, and about 800 bytes of RAM to hold the 12-bit color image (double that for the 32x32 matrix, double again for smooth double-buffered animation).

The operating principle here is obviously not very simple by the looks of it, and you'd be much better off starting with some low-level libraries with graphics libraries built on top of them (as described in the link above). Trying to do this all from bare metal would be a fairly major undertaking.