Media Manager

The Media Manager in the builder has 3 tabs.
My Images - shows the images that you have uploaded from your computer as well as the free images that were downloaded.
Free Images - this has a list of free images from that you can download and use on your pages. The images will be optimized and compressed when they are downloaded using the media manager. 
Upload - This tab provides the option to bulk upload images from your computer to use them on your page.