Measure and mark the wall where you will mount the table. The mark should be the finished height of the installed table minus its thickness. For example, if the table surface will be 42 inches above the floor, and the tabletop is 1-1/2 inches thick, mark the wall at 40-1/2 inches. Mark the center of center of the cleat and of the line where the table will be hung.
Locate the studs in the wall. Drill holes in the cleat to correspond with the locations of the studs. Screw the cleat to the wall through the holes.
To install the decorative brackets, hold them up to the wall and make sure they're plumb. Mark the wall through the holes in the brackets. Install self-tapping drywall anchors at the marks, and attach the brackets by screwing through the brackets into the anchors
Lay the table top over the cleat and brackets. Check to make sure it is centered, then attach it to the cleat by driving screws through the cleat into the tabletop from below the table.