Select a category on the right hand side.
Click on a thumnail image in the selected category to view a full size image.
Click on the image you would like to download, right click on the large image that appears and save that image to your computer.
A popup box will appear asking you to either open or save the file, select the save file option and select a directory of you choice for the downloaded image file. Once the file has downloaded you can close the popup box.