Circuit breakers step in and break the circuit in the electrical wiring when they sense something is wrong. It is fairly easy to fix a tripped breaker, but if it continues to trip, it may be time to have an electrician check out the cause.
Locate the electrical panel, which is often a grey box in the garage. The panel has all the breakers for the home, both inside and outside, in it. A tripped breaker is fairly easy to spot because the switch will no longer be on the same side as the others. The switch will be in the middle and will be showing an orange or red color. Simply turn the breaker switch off and then back on to get power back to that circuit.