Go to a swimming pool and learn slowly.

Learn how to go underwater. Go up and go down while holding your breath in the water (don't swim yet).

Next, hold on the bar at the side and flip your legs.

Next, go to somewhere in the middle (make sure not a deep pool) and learn to swim to the side bar. Learn the frog style first. Position yourself like a frog and swim....

Next, go deeper into the middle and do it again.

Next, learn various swimming styles...

Do it everyday, then you will learn naturally how to float naturally, and how to swim naturally.

Shortcut = go sign up for a professional swimming lesson.