How do I hang curtain rods if I can't find wall studs?

Use tension rods inside the windows.

U can use molley plugs, no need for a stud

Recommend using the plastic wall anchors. They now make one that you can simply screw into the wall without having to drill a hole and tap in, which are also flimsy at best.

i would say that the edges of the windows would have studs.

Use sheetrock anchors

drill a hole with a narrow bit. If you find a stud, great. Carry on with installing the bracket with screws. If you don't hit a stud, drill a slightly larger hole and use a plastic wall anchor. Then screw into that.

Is your wall sheetrock? Wall anchors would be your best bet if you don't happen to hit the stud.

you can use plastic anchors.

Longer screws, believe me there’s 4+ inches of wood around every window and at every corner

If you can't locate any studs, drywall anchors work in a pinch and give the extra little bit of support your curtain rods need. To install these, drill a pilot hole first, and then hammer the anchor into the hole before screwing directly into them.

Go to a big box home improvement store or a hardware store. They'll guide you to products that will anchor into the sheetrock firmly to hang items. Ask for wall anchors, toggle bolts.

You should use anchors. Make sure you buy the ones appropriate for your wall material and for the weight of the rod.

Employ wall anchors: These are your best bet in the event that the area where the rod needs to be installed lacks studs. Make sure the anchors you use are suitable for the weight of your draperies.