how can i format a jpg file and upload it to stl
It's a bit more complicated than that - are you trying to replicate a thing in a picture?
OR
You can create an SVG - which is a vector graphic file - and upload it as a profile to be extruded.
OR
you can upload a jpg to the Image Generator (in the Shape Generator drop down) and create a relief-type object based on the image's color tones.
Make sense?
Hasn't the Image Generator been discontinued?