24 bit HX711 ADC Reading
Start with the datasheet:

In the sections serial interface you can see the description of the method used to retrieve data from the ADC. Below snapshot is for reference:. 


DOUT should be connected to your MCU GPIO input pin. A low on this pin indicates that,the data is ready in the ADC.
PD_CLK is the GPIO output pin. You have to then send pulses on this pin while simultaneously reading the DOUT pin status.
Depending on the gain set and the channel selected the number of pulses needed will vary.
At the end of the data, SOUT line will go high again. 
So, This doesn't seem to be a standard interface. You have to develop your own bit bang style code for this   
You have to also take care of accumulating the 24 bits and combining it into one interpretable value.


Please post specific question if you are still stuck.