There are a couple ways to upload files to a media gallery: Drag-and-drop or view the new button:
First, navigate to the media gallery into which you want to add a file. Select a file from your computer, drag it onto the page, and when the drag-and-drop message appears, drop it:
Navigate to the media gallery into which you want to add a file or link, click New:
Specify details about the file or URL:
When you're done detailing the file, click Post.