Plug-in bedside lamps are convenient because you don't have to be hard-wired into a wall. This is an accent light, so use a low-wattage bulb so heat does not build up inside the vase.
Cut wire to the length you need — it is going to be plugged into a wall, so a little longer is better.
Attach the wire to the plant hanger using twist ties or electrical tape that is the same color as hanger. Leave enough wire to go through the vase and some extra to work with.
Attach the wire to the socket. Strip both ends of the socket wires. Connect the neutral wire — the one with the ridge in its insulation — to the silver socket terminal and the other wire to the brass socket terminal. Place the socket in the lamp, feeding the wire through the socket cap. Reinstall the socket's insulating sleeve and shell, pushing on the shell until it snaps in place. Once the socket is in, place the switch near the edge of the bed on the wire. Follow instructions on the switch package to install.