You can download Cura for free and it is fairly easy to use. I would use a photo editor to remove the stars on the jpg and then load it into cura with the lighter is higher option. You can then resize it - I don't know how big you want the end result, but the one I did just fits on my 3D printer.
If you struggle with it get back to me, but I am busy today.

Cheers,

Rob