Media Library is the place for you to upload and maintain all the media files such as images. On the top of the Media Library Screen menu will allow you to check all the media files sort by the used by relation such as Page, Style, View and so on. On the top right side of the Media Library Screen you can switch the display mode.
Media Library Folder
You can create your own folder to organize your media files. To do so, just click the 'New folder' button and type in the folder name.
After you create the folder, it will show on the root list. Click on the folder you want, the page will direct you to that folder.
You can upload images by clicking the 'Upload images' button.
To edit an image, click the 'Edit' button. In this screen, you can check the URL and edit the alt information.
Under the image, there is another 'Edit' button, which will allow you to edit the image such as crop, rotate and flip the image. After you finish, just click 'Save' to save it.