Positioning your Body
First things first, the starting position will be in the water, with the face outside the water. The starting position should be perfectly measured and delivered. If you make the mistake of sitting up in the water, your hips will drop too much, and your body will create unnecessary resistance. This error will slow you down, and make your tired very quickly.
Swim with your body being as close to the surface (water) as possible, and make the transition from the starting position to swimming as if you are lying flat on your bed (with a pillow underneath your head). Push your stomach out and up toward the ceiling while placing the midriff as flat as you can.
In the beginning, understanding the breathing pattern for the backstroke will be an issue, but with time you will definitely become consistent, and breathe evenly.
A common mistake (which you should be aware of at this point) is that most beginners keep the head too high up from the water. This mistake can occur when your head is too far backwards in hopes of keeping water away from your face.
While the right arm is doing its job, your left hand is extending to your side, leading the way, and helping you balance the entire body.
The little finger of your right arm goes in the water first, taking the entire arm inside with it, you will bend the right elbow, flex your left arm's wrist and push your left hand towards the feet.
Keep pushing with your left hand till the elbow is straight again and being lifted to mimic what the right arm just did. Follow the same technique as the right arm, and begin another stroke.
Legs and Feet Movement
As the arms provide immense power during each stroke, the legs contribute for forward momentum. Keep your legs together, as close as possible throughout the entire stroke. You will perform long but shallow kicks initiated from your hips.
Avoid kicking from the knees, always place them bent, and under the water. Your ankles should not be flexed, instead they are always floppy because you will have to turn your feet inward to gain the momentum.