Click on "add Cart notice" button to add new cart notice row.Then click on row title to configure that notice as shown in the image
Now chose any notice type from all available options.
If you want this notice to display only to certain roles , select specific roles for visible to option.by default its visible to all roles
If you want this notice to show only for specific period then select specific period for validity in place of all time valid.
To show button along with notice text enter button text and button href field as shown in the image.
you can also use variable inside notice text.