there’s a few techniques to do it. for instance, some players can rotate the stick so fast that a jump doesn’t register. then there’s the method osiriskidd mentioned, where you do a jab or something then try the 720. there’s a third method where you say fuck it and jump, just do the 720 in the air… but that’s extremely telegraphed, people are extremely suspicious of a Zangief who jumps. gotta get better at rotating, your hands are most likely capable of doing it but you’re just not mentally prepared yet. practice it.
also remember, and this is a very important point especially for people focusing on doing SPDs and final atomic busters and whatnot, you really need to pay attention to how you’re fighting. going around spamming final atomic busters doesn’t mean you’re gonna land them, gotta create situations to get them
edit: by whiffed green hand, I assume osiriskidd means a green hand that closes the distance between you and your opponent but doesn’t connect, leaving you to follow up with SPD immediately