If you upload a lot of photographs to Facebook or Instagram and use Adobe Lightroom, Publish Services is a great way to streamline the process. Its super simple to set up. All you have to do is open Lightroom, go to Publish Services (in the Library window) and click set up. From there you will enter your username and password for the accounts you want to set up and authorize them to access your page.
Once you're set up its as easy as dragging and dropping photos you want to upload from your Lightroom Catalog into the folder where you want the photos to publish to (Facebook, Instagram, Flickr, etc). One you add all the new photos all you have to do is right click and select Publish and your photos will be published to whatever site you selected them to go to.
Check out the video below for a walkthrough on how to do this.