Advanced configuration file help

i have no clue where to start when it comes to making a configuration file so if anyone can post really good tutorials would be nice as i cant find any good ones

what im trying to do :

i have an ore that drops several items at different drop rates and drop amounts, what i am trying to do though is add a configuration file that lets you change what items are dropped from that item and the drop rates. if anyone has good tutorials on how to do this i would be greatly appreciated