Hi @NicoleHa7
this has been an open product suggestion of mine for a while. In fact, you will have to find an online location yourself where your image can be uploaded and use that URL.
Ideally, this should be hosted on your own website. Alternatively (not recommended) a public image like pasteboard or postimages.
Careful though, that these images will likely be publicly available and should not contain any critical information.
Cheers from Switzerland!