Digital to analog converters, dual op amps.

Can anyone point me to a good tutorial on these and how to use them? i am stumped.

This is the obvious sort of thing to check with google, and then start reading.

From that link... A really good tutorial on Op-Amps and ADC's one of the best I've seen since I started learning electronics.
Tutorial - Experiment 8 - Digital To Analog Conversion Well worth reading from the start.
There is the ABC Thing created here at : This one is also a great tutorial Especially for the Arduino..