using A6 or A7 for blink led

hello i want using A6 pin or 7 the nano for led bacause i dont have ather free pin .if that possible or for lcd

A6 and A7 are for analogs only on a Nano.

A6, A7 are analog input only. Can't drive LEDs with them.

how add pin or how use lcd withe 74hc959

Use pins A6 and A7 to free up two pins you are currently using for inputs (buttons etc.). You’ll need an external pullup resistor.

Only need a pull up is you currently read a button (with pinMode(pin, INPUT_PULLUP)). If you swap an analog reading from A0 - A5 you're all good.

But if you want more useful tips, post a schematic (NOT a Fritzing breadboard view) of your circuit + a description of what it does.