To wire a single pole switch using a switch leg, you require power and a neutral at the switch box, not at the box of the device being switched. To wire using a switch loop, you need power and a neutral at the box of the device.
To wire a single pole using a regular switch leg, tie the grounds in the switch box together using a pigtail before connecting the pigtail to the ground wire on the switch. Connect all the neutral wires together, and connect the power wire to one of the black screws on the side of the switch. If there is more than one power wire, connect them together with a pigtail before installing the pigtail on the switch. Connect the black wire from the cable to the device being switched to the other screw on the switch, and screw the switch to the box.
To wire using a switch loop, attach the ground wire in the switch box to the ground screw on the switch before attaching the black wire to one screw on the switch. Color the white wire with a black tape, and attach it to the other screw on the switch. Connect grounds, in the device, together before connecting the white wire in the cable going to the switch box. Connect the neutrals together, and connect the black wire, in the cable going to the switch, to the device when you install it.