If you want to download more than one image. Select images as you go through your search. Once you have finished searching and with the images still selected, click the 'DOWNLOAD' link at the bottom of the page. You'll be able to download all the selected images.

A great way to add images to boards is to have the board's panel open. Select images are you go through your search. Once ready and with the images selected, drag & drop them into the board.