Here's what you need to know to get started. This is about as simple as it sounds. You just take your walk into the water. The deeper the water, the harder your workout will be. Find out which depth works for you and start there.
Most people choose a water level between the bellybutton and the neck.
You don't need a flotation belt to water-walk, but nonslip pool shoes or old tennis shoes may help. Swing your arms in broad sweeping motions to push and pull the water. For more of an upper-body challenge, wear webbed gloves. This increases the surface area of your hands, and thus, increases the resistance. Stand tall, keeping your abdominal and back muscles tight.