Connect Arduino pin9 to CS of 8×8 LED Matrix; Connect Arduino pin10 to CLK of 8×8 LED Matrix; Connect an external 5VDC (1A) to VCC of 8×8 LED Matrix; Connect external 5VDC supply’s GND, to the GND of ...

When connecting the LEDs in parallel (you can power it from any direction) always start connecting the ground (gnd) before you connect the live (5v) power pin. There is so much you can do with WS2812B ...