Click on the orange button ADD NEW. You will be directed to your image library on your computer. Click on the image you want to upload. The image will be added to your image library. The same steps apply for documents.
To add a video, Click on the Orange button Add New.
A box will appear asking for a Facebook, Vimeo, or YouTube. link. Enter in the link, click Save, and it will be added to your Library. If your link is from Facebook make sure that your video is shared publicly within your Facebook settings.