### Keep getting ?? as output instead of the desried sage output in sageexample

Hi!

So a total beginner in sage here so please try to refrain from suggesting too technical things here.

I'm trying to have some sage code results show in my tex file. After reading some parts of sage tutorial in example.pdf, I made another small tex file with

~~\documentclass{article}
~~\documentclass{article}

\usepackage{sagetex}
~~ ~~\begin{document}
~~ ~~\begin{sageexample}
~~ ~~ sage : E = EllipticCurve([0,3])
~~ ~~sage : E.discriminant()
~~ ~~\end{sageexample}
~~ ~~\end{document}

~~ ~~ Ran this tex file, then associated example.sagetex.sage file in terminal, then ran tex file again but all I keep getting is ?? Instead of the desired output.

What am I missing or doing wrong?

The first eror latex suggested is - Reference '@sageinline0' on page 1 undefined on input line 6.

Package sagetex warning: there were undefined Sage formulas and/or plots.
Run Sage on example.sagetex.sage, and then run LaTeX on example.tex again.

But what should I do?

Thanks you.

Edit: Sorry for not embedding the minimal working example right, I'm on mobile and new to this site so don't know exactly how to do that yet. Would appreciate pointers on that as well if possible.