How do I embed an image in a text box?
Click Browse Server.

This displays the entity picker. Your site Resource folders should be displayed
Upload the image file.

Hover your cursor over the folder where you want to store the image file then click on Upload File.
This displays an upload file dialog box.
Select the image to be embedded.

Click on the Plus Sign (+) to the left of the folder to expand the folder contents, and then select the image you want to embed in the text box.
Your will be returned to the image properties dialog box with a preview of the embedded image.