well if your image is flatened I don't think you can make a a part of it trans-parent.. it all boils down to layers. the eraser or selection mask will help you - Duplicate the BackGround layer - and trash the original.. your new "BackGround copy" can now be slightly erased to your desired requirements just grab an old image you like and use either a mask just make a selecion and when you are happy with it go to the Chanel and view the mask chan only and perhaps adjust the - when you find out wich way is the right way you can basicly Coose the level of transparency in the particular area you masked... exit the mask and DELETE it go a head n make a new layer and fill it white ( or something ) put it under the "layer copy to see the effect. or use an eraser @ 40% ( for example ) and -> try not go over a part of the image twice with the eraser <-