It's best to use a regulated power supply. 1.5 amps is usually more than enough. It really depends on how many relays you'll be running. The Watt Wrangler draws, at most, 300 mA. Hook red to positive and black to negative. Please be sure polarity is correct.

The pads marked 'Supply Voltage' will tie to one side of all the relay coils. Pads marked 'Relays' are numbered 1 through 8 and individually tie to the other side of each relay coil. When you set up Hardware these will be the pin numbers you assign to each device. Please be sure there are no shorts on your coil wiring before the wires are attached to the board.

This diagram shows how 3 relays would be wired.
Relay 'one' is on the top and relay 'three' is the bottom one.

Relay coils have no polarity so top and bottom side of the coil makes no difference. Just wire one side of each relay to 'Supply Voltage' and the other side goes individually to its respective pad.