There’s apparently a rate limit for new-new users, but the general idea is to either drag-n-drop the images into the reply or use the upload icon (the upward pointing arrow in the editor toolbar) to select the file.
That you can’t do, but if the static text is always in the same place, define another text box and plunk it where you want it. It’s fine to have separate overlapping shapes and the laser will trace / scan all of them, so be sure none of the letters overlap unless you want that to happen.
If you’re using Ignore empty vars to position either one or two lines of variable text in a text box, then the static text will be in the wrong place, but we’d covered some of the alternatives in a previous discussion.