I hope this is okay to post? I normally shade my characters very basically, but this time I wanted a bit more "mood" in it and let the beams of the window throw shadows on my characters. Now I know the shadow "bends" or creeps over the shape of the figures but honestly, I don't really know how without making a random-looking striped mess.
I might even know how to draw the shadows of the horizontal bars over the shoes and legs, but the vertical, wide ones leave me utterly clueless...

How would you place the shadws? What lines should I follow? I'm really not very experienced in "third party sadows", or those shadows from window beams in incoming sunrays.... or however you call these... I didn't find any tutorials on deviantART that address this exact issue so I'm hoping you guys could help me out?
Also is there any place to get or create precut/clipart assault rifles in all kinds of angles? Pimp my Gun unfortunately only has the side view... And I suck at straight lines or technical drawings, so unless I trace guns, they look awful. But most of all I really need some help with the shading please

"Trivia", these are 4 (notice the blurry foot) Israeli soldiers I sketched on the train to work once. For once, I got a seat. Normally I sit on the floor with barrels of assault rifles smacking me in the face at every turn XD Obviously there is no more resemblance to the actual guys in terms of hair or facial features as I was only discretely sketching the poses from the corner of my eye while trying not to get caught and disturb those darlings. All were paratroopers but I decided to put a black boot unit in the picture as well as I've been kind of focusing on red boot units (Paratroopers, some special forces) in my previous pictures and thought it was unfair.

Background is stock and proper credit will be given upon completion.