Even if you mean well and want to offer comfort, remember that the person who assaulted her took away her control over her body. Be a good listener. Assist her in getting the help she wants and needs. This may mean providing phone numbers, transportation, information, etc. Talk to someone else about your feelings about the rape.
Sexual assault can also be traumatic for.
You deserve support, too. Don't give advice or try to tell her what to do. Don't tell her what you would have done. Don't ask her why she didn't scream or fight. This can feel blaming, even if you didn't intend it that way.