I couldn't find any diagrams of circuits in houses, but I can describe it for you.  An electrical circuit is a loop, a circle, if you will, where electricity is sent to power so many outlets or light connections in a section of a house.  The electrons flow from the positive terminal of the circuit breaker box to all the electrical connections, and then back again to the negative terminal of the circuit breaker box, completing the loop.  The circuit breaker box is composed of lots of simple circuits, like the one I just described, which fuel wall outlets you plug small appliances into, usually 120 volts.  There are several larger circuit breakers that power appliances that have higher voltage needs, like your washer and dryer, about 240 volts.  Things like your air conditioning unit usually have their own circuit breaker and electrical connection, because they require even more voltage.  The purpose of the circuit breaker, as the name implies, is to "break" the circuit if one or more appliances is pulling too much voltage, causing that circuit to overheat, which could result in a house fire.