Multiplexer CD74HC4051, connections and parameters
I'm assuming + is +5 volts with respect to ground. Then you need to tie 6,7,8 to ground. Put a 150 ohm from pin 3 to the LED, and tie the LED to ground, not -. Then the LED should light with all control lines high.

Also, make sure the ground on this circuit is tied to Arduino ground.

Finally, the control lines must go to 5 volts. A 3.3 volt output is not guaranteed to work. See http://www.nxp.com/documents/data_sheet/74HC_HCT4051.pdf Table 7, Vih.