You can manage and view all your files from the Assets menu item.  Fixture allows you to upload images, videos, and other popular formats.  For images, Fixture will automatically resize the images into small, medium, and large sizes (as indicated below).   This can be helpful to optimize the speed of your site.

Files can also be accessed when adding media to the page.  For images, Fixture allows you to select a "responsive" size that will automatically populate the srcset field for you in HTML.  This is a great way to optimize page load speeds for mobile sites.