how do you save photos from various apps?

[DiskoDarci]

I would like to be able to save photos from various apps, say for example facebook & pinterest. I can't figure out how to save photos. I can take a screen shot no problem, but saving them would work so much better for me than that or emailing them to myself. Does anyone know how to do this? Do I need some kind of application?

cheers all !! Darci