On the left hand side of the steering wheel in you car is a stick that looks like a handle. When you push it up , or down , it turns on a light outside your car called a " turn signal".
This light lets other people in traffic ( do you see the other cars around you? Those have people in them.) know which way you intend to turn. Usually, most times, there is sufficient time for you to use the "turn signal" to get into the lane which is closest to the direction you intend on turning.
For example : when you know you have to turn right in a couple blocks on Any Name Street, you use your "turn signal" to tell the drivers around you that you would like to get in the right lane. Then, when you get to Any Name Street you can turn right FROM THE RIGHT LANE . Turning right from the left lane , although common in this great city , isnt safe and should not be legal.
Apply the same rules to turning left.
More next time, on obeying traffic signals and driving only one car per lane.