Hi Fernando,
Just tie Q7 (pin 9) of the first chip to the serial data input (pin 10) of the next chip. For a 24 bit port, tie all three clock enable input lines together, and the clock inputs together. Hope this gets you started. Keep a close eye on your data sheet, as this will help you a lot. Other questions, or if I haven't been clear: just ask.
Best wishes,
Robert
look
you have a 8-bit shift register couple the SERIAL DATA OUT pin of rigester Carry 8 most significant bits to to the SERIAL DATA IN pin of second least significant 8 bits and so on...
when u connect it Enable Parallel Load Pin to Load Data then on each clock pulse when Left or Right Sgift is enabled you can get serial data..