as far as I'm awre you as individual trader will not be allowed to participate in Opening or Closing Auctions anyway ... only market makers etc are in it;
But in general Aucton principle is prety simple and it consists of two main periods (there can be more than two in some cases where Auction extention periods are reqired). so first there is Auction Call Period aprox 10 minutes (closing aprox 5 min) and then there is Auction Match Period aprox 30 seconds. During Call period - orders are entered into the Order Books, during this period the orders are not automaticaly executed/crossed even if there is a match bid/ask. Only Market Orders and Limit orders are allowed; Once it is done then the Match period kicks in and once it is activated orders can not be changed/deleted etc during those 30 seconds ish, as the orders are crossed/executed;
Hope That hels ... and btw good luck with your venture into the trading ... take it slow and easy ..