If there is a stained glass shop in your area, you could ask them how to do this...it has a lot of different factors to consider....cuz it depends if your glass is opaque or clear as to how different lighting would work/look. Or maybe if it is clear glass, you may want to add a frost effect to it to block the sight of the lits? dunno.... interesting project tho!Hope you keep posting about it!

My aunt got a window from her church... they had it framed and a light put in the back. It looked beautiful when the light was on ... well when the light was off too but especially when illuminated. Not sure how it was put together but it can be done ... I think the frame was thick enough to hide the light at the top.

Try googling light box stained glass. That is what you want-a liht box, modified to hold your window They are easier to make yourself than to purchase.