The message of the day is normally, but not exclusively positioned in the bottom right hand corner of the dashboard. For simplicity, it typically consists of the following two widgets/panels:
To edit the text panel, double click anywhere on the text. This puts you in basic edit mode and the text can be edited as needed:
Edit as needed.
Submit the edited text by clicking to the right of the edit area:
Save any changes made:
Hover over the image panel and click on the 3 virticle dots in the top righthand corner to reveal the drop-down menu and click on Edit:
Double Click on the Image source
Enter the URL of the new image here:
Preview and select the new image. If preview does not work, check the URL, and Image type are correct. Make sure your image is in a format supported by web browsers (commonly JPEG, PNG, or GIF).
Select your image size/fill option for the desired appearance
Apply the changes and check that the dashboard has the desired appearance
When satisfied, ensure your new edits are saved.