When an Orphelins bet is made manually, five chips are placed on the grid part of a roulette table betting layout so that eight numbers are bet on. These are straight up, and split bets and the payout odds are 35 to 1 and 17 to 1, respectively.
The Orphelins on Roulette are the numbers (orphans) that do not belong to the two sections of the wheel covered by either the Tier du Cylindre (third of the wheel) bet, or by Voisins du Zero (neighbours of zero). There really isn't anything more to it than that.