If you want text baked into the image you’re using, FancyMenu itself doesn’t add that for you—you have to edit the image in an external editor (Photoshop, GIMP, etc.), add your text there, save it as PNG, drop it into config/fancymenu/assets/, and then use it in an Image element or background just like any other texture. That’s the “baked” approach.
If you just need text that can change or use placeholders, use a Text element with Markdown/formatting instead (see the Text Formatting guide). But for fixed text inside the graphic, editing the texture beforehand is the way to go, then point FancyMenu to that asset via the resource chooser—see the Resources page for how resource paths work.