Your ban information:
http://www.opticraft.net/index.php/page,BanLookup.html?username=X2SaraYou were banned because, what you said, cupcakesmile2 was on your account. I'm not fully convinced that it was her all of the time, but I will give you the benefit of the doubt. Cupcake
was banned on 4th December and her being on your account wasting our time by asking for you to be banned and ban evading is obviously not what we want. Your account is your responsibility, therefore you must protect it from anyone else accessing it even if you trust them. Make sure you fully log out after using Minecraft, if you can't do this you will be treated with the same punishment as the person being banned.
If you understand and are willing to do what I suggested, I will unban you. cupcakesmile2 on the other hand will stay banned as they have a perfectly valid reason to be banned.