Maybe start looking at data sheets of simpler stuff, and then work up.
I like this data sheet site: http://www.datasheets.com/search/ You need to sign up but they don't bug you.
Type in LS595 for example. Look at the Arduino ShiftOut page:
http://arduino.cc/en/Tutorial/ShiftOut Hook one or two of those up while referring to the real data sheet.
My favorite set of 20 cent chips is HERE:
..and the data sheets are linked there...