Translucent image button

hi, I was wondering if there was a way (even if it includes editing the code, I would be willing to do that to make this work) to make image buttons translucent/semi-transparent. when I tried it it just turned into a solid non transparent image. I appreciate all the help I can get! (if theres a wiki page that explains how to do this link me, I might just be an idiot for not finding it)