If you’re viewing your files using the Grid View, simply click on one of your media files and you’ll be presented with a pop-up window that displays the relevant properties for that particular file.
After updating each field your changes will be automatically saved. You can use the arrow buttons at the top of the pop-up window to navigate to the previous or next image. Click the ‘x’ in the top-right of the pop-up window to return to the media Grid View.
Video Tutorial: http://kampus.rvhobo.net/media-library/
Documentation: http://easywpguide.com/wordpress-manual/media-library/editing-the-file-properties/