At the moment, you must host images to a webserver and then copy the links. Uno is planning to introduce a feature that will allow users to upload images directly into their uno accounts. I've already signed up, so I'll receive a notification when this feature becomes available.
Thank you; I intend to use Uno overlays for the first time in our church this coming Sunday. I however I haven’t been able to use an image in the uno overlays as a logo. Any ideas? Thank you.