Backstroke
Here are the basics for swimming backstroke.
Backstroke is very similiar to freestyle, just flipped over. A lot of freestyle specifics are repeated on this page.
Rotation is still important; picture body rotating on an axis. Shoulders should go from pointing to the floor to the ceiling.
Eyes should stay looking at the ceiling (head should not move/rotate.
Backstroke Kick Specifics
Keep straight legs; avoid bending knees (should not look how it does to pedal on a bike).
Move legs up and down, pushing water behind body.
Keep feet toward surface. I tell my swimmers to make white water.
Backstroke (arms) specifics
When pulling underwater, keep fingertips just below water's surface and sweep hand down toward feet, pushing water that direction.
Brind hand out of the water near your thigh (keep elbow staight).
Make a rainbow, going from near the thigh and placing hand in the water arm's length away from head (rainbow direction should be from feet to head).
Breathing
Breathe in through mouth and out through nose.