You can start by uploading your first media item by clicking on the Upload media button in the middle of the page.
If you already have media, you can upload new media by clicking on the Upload media button at the top-right.
Clicking on the upload button will open a new modal where you can drag and drop a file or select one from your computer.
With the file selected, click on the Upload button to upload the media item.
Once the upload is complete the modal will close and your new media item will be visible.