Lighting Mask

Hi…im trying to make a lighting mask for a picture…*.bmp (or should it be .jpg or?)

But it doesnt work…i followed the tutorial for making a lighting mask for text…that did work…i tried a lot, but dont know it anymore…please help!!
thnx…

Start from the begining the tutorial. Are you sure you have 3 layers as it says? If you put an image make sure that there is nothing else except the letters.