### Elliptic Curve functions don't seem to exist?

Hello. I'm trying to design a puzzle that involves finding a weakness in an elliptic curve cryptography application. I see descriptions of past puzzles that others have made, but they use SAGE with commands like "E = EllipticCurve(GF(c), [a, b])". From my attempts to uses SAGE online before installing, and from looking through the manual, it looks like there aren't any functions called EllipticCurve or for that matter GF. (They show up with red underlines in the online command window.) But then I did try running a similar command anyway:
"sage: p = 354990952970600489
sage: E = EllipticCurve(GF(p),[9326,1376127157])"
and got an error about this being prime or something similar -- don't have the error in front of me. So do the functions exist or what? I'm puzzled because the tutorial doesn't seem to work despite being written specifically for SAGE.