you need use node texture clouds or node texture massgrave and node color ramp for color range and connect color ramp to output material, if you need mix and animation this texture for game use vector math nodes add and node substract before textures for rolling UV gride for this connect from geometry node uv port in first vector math node for secondary port connect mapping node and for node mapping connect time node or random - for assign values
Still struggling. That tutorial did not solve it. It should be SO simple ! For example look at this Shadertoy - Water Shader Sample (shadertoy.com) - How do I put that in Blender. Is there a fragment shader node ?