All you need to do is go to the theme downloads page and download the latest version of your theme. All of the download links have just been updated. The version number may be the same as your current theme, but they all now contain the MailChimp Optin Widgets. You can read the MailChimp Optin Widgets Tutorial here.
For more information on how to update your Appendipity Theme, click here.
We hope you enjoy using the new MailChimp Optin Widgets. That is it for today.