To start off, you are going to need to get power to your new circuit. Therefore you are going to need to run a wire (12-2 gauge wire for 120 volt circuits) from the circuit breaker to a member of the circuit, preferably the closest outlet or switch box. This wire is called the home run, because it is the wire "running" from "home" (the circuit breaker panel) to feed your circuit with electrical power. Drill holes through the joists and/or studs you need to get from the circuit breaker panel to the outlet or switch box. Use a hammer and staples to fasten the wire to the studs or joists. Use a wire cutter for cutting the wire at one end.
Now that you have the home run and power to your circuit, you need to connect the dots. In other words, you need to feed power to the rest of the circuit. These wires connecting the circuit together and giving power to an item are known as "feeds." For example, let's say that your circuit consists of 5 plug-in outlets and 2 switches. Let's also say that you ran your home run feed to an outlet. Now you simply connect the dots, or the boxes. Run a feed from the outlet with the home run to the next outlet, then to the next, then to the switch or whatever may come next until all the 7 boxes are connected with a feed. Keep your runs simple and easy by stopping and thinking about how you are going to run the circuit before you do anything. Look for the closest and easiest feeds. Then drill holes through the studs or joists needed to run these wires where they need to go. Then run the wires, cut them when needed, place them in the boxes and staple them to the studs and/or joists to fasten them.
Now you have power to all the outlet and switch boxes throughout the circuit. Next you need to run wires to the devices the switches in the circuits control (lights, fans, switched outlets). To complete this step, run wires from your switches to the devices they control. These wires are known as "switch legs."For example, let's say you have a switch which controls 2 lights. Run a wire from the switch to the closest light box first. Then run another wire from the light box which has the switch leg from the switch to the second light box. You have successfully run switch legs for that switch. Remember to fasten the wires with staples. Next jump to your next switch, and the next, and the next, until they are all run. Now you have your circuit wired!
Finally, double check your work. You don't want to miss a feed or switch leg and find out after the drywall and paint and plaster has been applied that you missed something. So take the extra time at this point and retrace your steps. Physically follow the wires and make sure they are all going where they are supposed to.