ADC of PIC micrcontroller 16f877

dear frnz
m working on an ADC of PIC micrcontroller 16f877. while testing adc showed to many fluctuations,but after that when i added 10 microfarad capacitor at the adc input it stopped fluctuating (to a extent). is this method correct? is yes then please explain me how and if no then wht is the correct method to stop fluctuations in adc.

thnx

You need to provide many more details - it sounds like you're feeding AC to the input?.