I can't do it off of Facebook. They changed their format and you have to save the image to your photo file then you can load it here as a regular photo. I can't copy and paste from one site or within the site (here) I never did though. I always save the image to my photo file.
I just hold on any image and select "download image" and you find it in your gallery, either screen shots or downloads.
Some pictures won't copy so you can hold your volume down and off buttons at the same time and take a screen shot. You'll find the copy in your gallery also. With this new android you almost always have to edit each picture copied with the crop feature to get rid of the phones borders ect.