How to Put Facebook Photos on Instagram
Not all photos you post on Instagram have to be taken with the Instagram app. If you feel so inclined, you can post images to Instagram pretty much from anywhere, including from Facebook. There are, however, some limitations. Facebook may own Instagram, but connecting your Instagram account to Facebook only enables posting from Instagram to Facebook, not vice versa. To get a Facebook photo on Instagram, you'll need to jump through a few more hoops.
Save the photo from Facebook to your device's photo gallery. How you do this depends on the device you're using, but usually touching and holding the photo brings up a contextual menu from which you can save it.
Open the Instagram app and tap the "Camera" button.
Tap the "Gallery" button. This button shows the last photo in your device's photo gallery.
Tap a photo to select it. Adjust its scale and positioning with the usual touch gestures and then tap "Crop."
Apply effects to the photo, if necessary, and then tap "Next."
Fill in the caption and tags and set the various sharing options to your liking and then tap "Share" to post the photo to your Instagram feed.