We have had a series on the swimming basics, so lets start with the basics of the freestyle pull.
Rotations: The rotation drill is when you have your arms by your sides, you are kicking and you are rotating your hips and shoulders together, with your core being the bridge between the two body parts. I like to think rotate the hips, keeping the core tight, and a slight lift/arch in the lower back. Normally if you think rotate the hips the shoulders will automatically be in line with them. Some times the hips can be late rotating if we focus to much on the upper body rotation. On the upper body rotation we want one shoulder to the side of your check, while the other shoulder is above water feeling air. The chest is turned in a direction toward the lane line. They you switch driving the hip and shoulder down and forward while the other shoulder and hip come to the surface. You are rotating. Put a 3 or 6 count on it to stay consistent. As Always the body stays in a line. Take a look at the Freestyle videos for a rotation example.
Now we add Arms:
Stretch through your armpit reaching forward as far as you can and grab as much water as possible. Hands strait forward or pinky slightly up wen you reach, pick which works for you. The index finger can never turn up to the surface. Slight hand turn in pulling down your midline, bend your elbow about 45 degrees, lock the elbow, use your lats and core during the pull ROTATING your body, all while staying on your midline until you finish your pull. The elbow is up under water, fingertips are down and the hand and forearm are throwing water back to the wall behind you. I prefer to say grab and throw instead of anchor and pull. The main goal is to find the catch and pull that works best for you.
This is suppose to be the basics so here it is simplified: Reach on the line, pull down the line.
1 arm freestyle is a good drill to review on the videos to get power and timing.
Good luck and Go Swim!