Using transparent images in Unity

I am trying to make a prefab that is basically a image. To do this, i have made a cube and put on it an image i have. But i have a problem =/

My image have transparent background, but in Unity, it simply doesn’t have. When i put the image on the desktop OR open it on any image editor, it appears as it were to be, transparent. But when i import it to Unity, it’s background automatically change to black, and the transparency doesn’t exists anymore. I have put a transparency shader, but it still doesn’t show the transparency, but instead, a black background.

This is really annoying me, and i am almost finishing a game. I don’t have much time left to finish this, otherwise i will mess up with all my work, and this is the ONLY problem i have. Can someone help me? Like, NOW?

Change your material rendering mode to cutout, fade, or transparent and it will work.