Can't view color with Diffuse BSDF! I was following a tutorial on how to make realistic trees. In one part, the person makes a leaf and uses nodes to make a material. He uses a color ramp and the leaf turns black and white, but the person was able to view it in color when he clicked on  Diffuse BSDF. However, I still see it as black and white! I fear I have done something wrong and if I continue without trying to fix it, I will mess up my mesh later on.

I searched everywhere on Google, but I had no luck. 
Here is a screenshot:
With the Image texture Add transparent and Diffuse BSDF with Mix Shader. With the Alpha of image texture connect to Factor of Mix shader as shown in image.



Another simple way just activate Image as plane addon in Blender. Press  Shift+A Mesh -> Image as plane. Navigate to the png image. Thats it Press Shift+Z to render view.