Remove the little plugs holding the black cover down at the front of the engine closest to you. There should be 4 on the bottom and 2 on both the left and right sides, poke a flathead under the center of the plugs top and lift.
Move the black cover aside, then find two tabs (a total of four for both headlights) that can be pulled up. They need to be pushed back a bit to come up. Remove the caps on the outside tabs. The tabs on the outsides comes up about halfway, and the ones on the inside come out completely. With the tabs released, the headlight should slide right out the front of its frame. Unscrew (not much) the wires on the old headlamp and replace them in the new one.
Getting the lamp back in and secure can be very difficult depending on the condition of your tabs and so forth, a second set of hands usually makes the task a lot less painful.