How to power a 12V solenoid
You're trying to control the solenoid from an Arduino?  Or from the wall outlet?  Is this 12V DC or 120VAC.  Do you have a datasheet?

If you want to control a 12V solenoid from the Arduino, you'll need to get a GPIO to switch a 12V supply for you.  You can do this thru a transistor (smaller arduino IO voltage controlling the base of a MOSFET that's switching a 12V source). 

Do you have a spec on the solenoid?  Also, have a look here at the switching circuit.  Plenty of information out there re: solenoid switching.

http://www.electronics-tutorials.ws/io/io_6.html