Check beneath the counter top for a set of mounting brackets. If none are present, purchase a kit from your local hardware or appliance store.
Carefully pull the dishwasher out from beneath the cabinet.
Slide the lip of each bracket into the mounting holes on top of the dishwasher collar. Bend the tab above the mounting holes over the bracket with a pair of pliers.
Push the dishwasher back into place carefully. Fit an electric drill with a Philips screwdriver bit, and screw mounting screws through the brackets and into the underside of the counter top.