If your CMS does ot allow you to write HTML code directly, you'll need to upload a PDF, not a JPEG--it's the only way to do what you want.
I'll have to inquire on both the HTML question and the possibility of uploading a PDF. I wonder if the JPEG is required for the variable length. That is, it doesn't matter how long the JPEG is, the window resizes. It's just particular about width.
If a PDF can be uploaded I would be left with only one problem, albeit an important one. I go from Word print to PDF and, if I open in Preview, the link remains. However, if I open in Graphic Converter the link is gone.
Therefore I would need to be able to do my simple edits in something that doesn't break the link.
ryck