Remove any easy-to-remove legs, drawers, shelves or doors; you will paint them separately. Remove any hardware such as knobs and handles. Place them in a plastic baggie so that you don't lose them.
Sand the surface just enough to roughen and take the gloss off the surface of the laminate. Do not sand through the laminate layer. Use a sanding block for sanding small flat surfaces. Circular sanders will make short work of larger surfaces. Use a few sheets of sandpaper for corners, nooks and crannies.
Wipe off the sanding dust. Make one final rub with a tack cloth to be sure that you remove all of the dust particles.
Place the desk or its pieces out on a canvas on the floor.
Apply 2 to 3 very thin coats of primer to the surface with a spray can or paint roller. The thinner the coats the better. Allow each coat to dry for the manufacturer-recommended amount of time before applying the next coat.
Apply 3 thin coats of melamine of the color of your choice. Allow each coat to dry for the manufacturer-recommended time between coats. Allow the last coat to cure for the manufacturer-recommended amount of time (usually six days for most melamine paints) before moving on to the top coat.
Leave the last melamine coat to cure for six days (or the manufacturer-recommended amount of time) before reassembling the desk and reattaching the hardware.