When you conduct an image search, the results are displayed as miniature images called thumbnails. If you scroll over a thumbnail, you can add that image to your Gallery by clicking on the ‘Add to Gallery’ icon on the thumbnail. From ‘My Gallery’, you’ll be able to view and select the sizing you’ll require.
Alternatively you can click on the image itself, which will bring up the image on your screen to full-size. You will see to the lower right of the image the same icons and the words “Add to Gallery”