In simple terms: Odds with a -  indicate what you'd need to bet to profitR$100. Odds with a +  indicate how much you'd profit with aR$100 bet.
You choose between 3-15 events and then you choose how many events you want in the parlays. The Round Robin will consist of every possible parlay combination of that number of events, or ways,  available within the amount of overall events you choose.