Please tell us what you have unsuccessfully tried (eg. post some code.)
While this question is important beyond just one example, do note that transparent textures are not a good way to create a window in a wall. You would want to model an actual hole in your mesh.
While this question is important beyond just one example, do note that transparent textures are not a good way to create a window in a wall. You would want to model an actual hole in your mesh.