This in done in Photoshop Elements. But the settings are the same as in Photoshop, only the interface is different. Here is a quick way to some really neat edges. You can play around with this in many ways, but this gives you a good start.
The name describes the edge that is created in paper making, when the sheets are torn apart from the roll of paper that is created by machine. You will have 2 deckles on opposing sides, two edges cut from the roll itself. When the paper is made by hand (for fine art and books), the sheets of paper are made individually and the sheet has 4 natural deckles. They are uneven and can be very decorative. The sheets are created by layering fibers on top of a fine wire mesh.