Messages are created via the Packages module.
In the Packages selection window, select the package for which you wish to create a message, and then click Messages.
To add a new message, click NEW MESSAGE.
In the Add new message window, enter the message details. To add recipients, to the right of the To field, click ADD. In the Add people dialog, you can select the recipient of your message.
To add people, select them from the dropdown list and then click Add.
When you are done, click SAVE. Click CC to carbon copy other people.