John Locke's theory of property is very complex, but its most important component is actually quite simple. According to Locke, man turns the common fruits of the earth into private property by mixing his labor with them; that is to say, he turns the natural environment into his own private property by working it. On Locke's account, labor is a very broad term which covers everything from picking up acorns from the ground to catching fish in the sea. The main thing is that in each case, the individual mixes what's already his—his body, his own person—with what has been provided for all—the earth's flora and fauna.
In Voltaire's Candide, El Dorado is the famous city of gold, a shining utopia in which no one has to work in order to survive. Unlike the competitive, acquisitive world of Locke, El Dorado is a society in which private property has no meaning. The fruits of the earth are there for all to share, as in Locke's state of nature. However, the big difference is that no one dreams of turning those fruits into private property by mixing his labour with it.
The value system of the native inhabitants really couldn't be more different to those of the rapacious Europeans who, as the Old Man of El Dorado ruefully states, would willingly murder everyone in the fabled city to get their greedy hands on their land. This is because El Dorado is a land with an abundance of gold and precious stones. This is a place where children play with sparkling jewels before casually discarding them when they get bored. As the El Doradans have no concept of private property, no understanding of "mine and yours," the precious jewels—or "pebbles" as they call them—belong to everybody. It's fair to say that this is a society which Locke would not have recognized.