MacBook Pro (Retina, 13-inch, Mid 2014) with 8 GB 1600 MHz DDR3

I bought a Seagate external HD 500gb with my Mac. Recently started using Photoshop and Lightroom, which take up a ton of space. I was thinking of moving my entire Iphoto to the Seagate to free up space, is this possible. If so, how would I go about it? Thanks in advance.