You're camera may have the ability for you to modify WB in camera and save it as a new photo, and view the changes on screen.
You may want to read up on your camera's ability in this regards.
I first started learning about WB whilst playing with my camera in the bathroom. The white tub etc was off white in a few test shots. I learned how to take a photo and change it in camera, then I learned more about the WB different lighting situations, and custom WB.
I say read your manual a bit, then play with your camera. You have to learn to understand your camera features then you'll be able to understand WB better.