Gmail and BUmail are not the same thing. Although your Butler email and password can get you logged into the Butler Google Apps, at this time your Butler email cannot be imported into Gmail. In fact, Gmail has been disabled and cannot be accessed when you are logged into Butler Google Apps. To use Gmail, you will have to use your personal Google account.
For more information, visit Butler IT's FAQ page for Google Apps.
Here is a beginners guide providing information and basic actions to use Gmail.
Here is a broad overview of all the features of Gmail, including a cheat sheet, keyboard shortcuts, and tips for optimizing your inbox.
With a Google account you can video chat up to 9 other people through Google Hangouts. While this is a feature of Google+, it can also be accessed through Gmail.