When you upload media to your account, it goes to the My Media folder. This folder is not visible to anyone else until you upload it to an application!
To access your media, navigate to the top right corner of your screen, click on your headshot, and select My Media from the dropdown menu.
Then, click within the box labeled Drag and Drop or Select a File to Upload to upload your media!
Your media will upload, and then begin processing, and you'll see a progress bar, shown below.
Make sure to wait till your media finishes processing and you can see a preview of your video before navigating away from your screen.