Well start off with grabbing SteamPipe's FFP multitexturer, no shaders required. Edit the textures so that the top 2 textures are water caustics, and the bottom is your actual terrain texture. Then edit the alpha channel accordingly. That shouldn't require any coding Then examine his code.. and research texture scrolling... and that should give you a pretty good start. Look at other effects as well to see how they achieve the movement.