From the admin toolbar, navigate to Content > Add media > click File, Image or Remote video.
Depending on which option you chose:
File or Image: Click the Choose File button, and then browse out to and select the file to be uploaded.
Remote video: Enter or copy/paste the Video URL.
If you chose Image in Step 1, you’ll need to enter Alternative text if the image conveys information (be descriptive, but don’t write a novel; if the image is of text, write out the text) or “” (double quotes with no text in between) if it is a decorative image (i.e., just for looks).
Click the Save button.
Edit/Delete/Replace Existing Media
From the admin toolbar, navigate to Content, and then click Media.
Search or browse for the media file you want to modify.
To the right of the media file, either click Edit, expand the drop-down menu to select Delete, or click Replace file.
Depending on which option you chose, you can:
Edit:
File: Change Description and/or delete the file and upload a replacement.
Image: Change the Alternative text and/or delete the file and upload a replacement.
Remote video: Change the Video URL.
Delete: Confirm media file to be deleted.
Replace file: Browse to and upload a new file.
If you edited or replaced a file, click the Save button; if you chose to delete a file, click the Delete button.
Book traversal links for Managing Media Files (Documents and Images)