Three ways:
#1 Just drag and drop. Click and hold on the pic and then drag it to your desktop, or folder. Done
#2 Right-Click and choose "Save Image"
#3 If it is an image that opens up, either #1, or Right-click on the pic before seeing it large size and choose "Download Linked File.."
Then you can always Ctrl-Opt-3 or Crtl-Opt-4 or Crtl-Opt-4-Spacebar to take a pic of your display, chosen area, or window of choice.
Hope this helps. If there is a particular image, or setup you are interested in, just ask.
