Correction to Les's diagram!
In his diagram, Les shows power coming in to tab "87" on each relay. This is supposed to be the output, and power is normally supplied to tab "30". "30" is the usual source for battery power on switches and relays. This will help avoid confusion when working on things in the future, and also some relays have more than one "87" tab. Using the "87" for output when there are two "87" tabs is handy; you can run power to two things this way, each on their own tab.
Care should be taken not to confuse a relay with two "87" tabs with a switching relay (red stripe) one that has an "87" tab and an "87a" tab.