The traffic pattern is a simple set of paths in the sky that allow pilots to fly to an airport and land in an orderly fashion. This standard set of paths lets us know where we can expect other aircraft to be and makes it easy to communicate where we are.
To fly the pattern a pilot will depart and climb straight ahead until the airplane is past the end of the runway and within 300 feet of reaching the pattern altitude (usually about 1000 ft above the runway).
Then he will turn downwind soon so that the downwind leg is about 1/2 to 1 mile from the runway.
There are a number of steps to take to land and they begin on downwind (or sooner). Is the pre-landing checklist complete? Do that first.
On downwind, choose a power setting that will allow you to maintain altitude with your airspeed within or just slightly above Vfe (top speed of the white arc).
Then wait until you are abeam the runway, meaning that you are passing the end of the runway where you intend to touchdown and it is 90 degrees to your left. Once you are abeam reduce your power so that the aircraft may descend. Expect to add just a little bit of back pressure to the yoke so that the aircraft slows down while descending. If your speed is outside of the white arc then do not let the plane descend yet. Instead slow it so it is within the white arc. Once you are within the white arc below Vfe you can lower your first notch of flaps.
Next, you need to turn base. When to turn is a bit of a judgment call depending on a lot of factors including wind, power setting, speed, altitude, etc…. In general, you can usually turn when the touchdown point is about 45degrees behind your left shoulder.
Once you turn base lower the flaps another notch. Then look at the runway and decide if you are too high or low. Look at your airspeed and decide if you are too fast or too slow. There are some tricks to deal with this but the simplest thing is to add power if you are too low and reduce power if you are too high. If you are too fast or slow you can adjust with both power and pitch.
Turn final soon enough that you don’t overshoot the runway and feel free to make an earlier shallow turn if it helps. Then work to get your aircraft lined up with the centerline of the runway. Don’t let yourself drift around. Instead, aim to keep the plane lined up as perfectly as possible. As you get closer to the runway and you are almost over it go ahead and add in the rest of your flaps.
All the steps above should be taken smoothly in order to create a nice stable approach from the pattern down to the runway. Practice this until you can get from downwind to the runway and float in just over the numbers at the right airspeed.