Place the blurred bitmap behind the glass and lead (Ctrl B).

Select the bitmap and then select the Transparency Tool. Select Flat from the Transparency Shape drop down list and Stained Glass from the Painting Mode drop down list. Move the slider to 30%.

This adds the appearance of light passing though the glass and makes the glass look, by degrees more transparent.

On the next page, I'll show you a little discovery I made that will make the glass really look transparent.