If you ask a question, be kind and at leasT ASK THE QUESTION instead of just using the title and posting some images. Also, the two texture links your provided both lead to the same picture.
Now, for the problem at hand. By default, the simple geomatric shapes included in the Unity editor are one-faces, that means that each side has only one polygon looking outward (or up, in the case of the plane). You could either copy the plane, flip it around, and put it slightly below the original one, or create one yourself in your 3D modelling application.
Go through this tutorial [Unity3D] Creating underwater effects in Unity3D for details as to how to create underwater effects.
This tutorial specifies why the water will not be visible from inside the water body and how to overcome it by using a second flipped plane.