Swearing is still considered rude and uneducated from both men and women, though you do hear it more in casual speech.
Another thing to remember: swearing isn't the same around the English-speaking world.... I mean, using the same swear-word doesn't have the same effect everywhere.
If you're asking if it's okay for YOU to say "shit", then no. James has explained why. It's best to avoid using vulgar language (and slang) until you're absolutely, definitely sure it's OK with the people you talk to.