How to model a complex shape like this ornate window? I'm stumped. Two hours now and I can't get it to work. How would you make this window? You are a godsend if you can help. (see the little red circle on the image)

I can create the outer part of it, but unlike a square window which I have no issues with (extruding in, deleting faces, etc), I can't figure this one out.



Thanks!
There are many possible ways you could go about it, but perhaps this will give you some ideas.
Instead of thinking of the window as a solid chunk, think about the separate parts (sill, frame, bar things, glass, etc.) as, well, separate.
For example:

Model the frame:


Add the bar things as separate parts:


Add the glass:



The result here is admittedly pretty terrible, but in my defense I was hurrying so that the the gifs wouldn't be too big.. If you spend a little more time adding details to each of the components, you can get something more like this:

By adding even more detail (e.g. screws) to the places were parts are attached, you might make it even more believable.