Basically all you need to do is make a black square (0,0,0) in a paint program like photo shop and save it as a .jpeg Drop it into the textures file where you can find it easily. I named mine *cloakof invisability, so It's on top. Then when you want to use it , load it in transparancy then set the max and min to 95 and 85 repectively to start. I play with the levels till I get it to where I want it. Add a color to tint the glass if you wish and add a bump map if you want for more interest as I did with the girl in the vase.