How can you understand ADCON?

Hi All,
Trying to understand how to set "ADCON". We start with ADCON0, then ADCON1, then ADCON2. Is this the same as setting RA0-7 to either a 1 or a 0? 1 meaning the RA is analog and 0 meaning it is digital? Then would ADCON0 apply to the RA0-7 pins and ADCON1 the RB0-7 pins and ADCON2 the RC0-7 pins? If you do not define an ADCON what happens? YES, I did look at the data sheet for an 18F2520 and all I see is text! I have read other posts and nothing seems to be very clear.

Thanks, Ed