Use the left mouse button and click on the photo to open an image window with a larger photo.

Use the the "File > Save As..." commands in the tool bar at the top of the image window

OR

Use the right mouse button and click on the larger photo.  Highlight and left click "Save Picture As..." in the small window that opens.

Identify where on your hard drive you want to save the photo (e.g. My Documents). 

Click "Save."