This is a step by step guide on how to replace and existing light with a new Double Switch. The process isn't complicated and taken step by step it can be done in a reasonable amount of time.

FOR CEILING LIGHT EXHAUST FANS:
You will connect the blue and black wires from the light to the black wire to the switch,

FYI:
1. Always make sure the lines are NOT live while you are working on anything electrical.
2. Make sure everything is up to code.

My project was to install a ceiling light exhaust fan, then install a double switch so the vanity light can run off of one switch, and then have the ceiling light exhaust fan run on the other switch.

http://www.pauliojr.com