which microcontroller you use? . If you are a beginer in microcontroller beter you select PIC microcontroller or 8051? select your controller and read the data sheet of the controller which contin the registers associated with the ADC module, identify the registers and bits and then read the steps to program the ADC and configure it, Better you can use some simulators for testing your program
you try to use ADC0809 ....it is from national and 8 bit ADC.....interfacing is simple....only the thing is that you need to have external clock gererator designed for your requirment.... Look for any 100Khz or 50 Khz generation circuit ....you will get an idea....