You can edit the content of the Alert Button by going to Content > Sections > Alert Button.

The Description field controls the text listed on the button itself, and there is a field where you can put the name of the icon you want to use. A full list of your site's icons can be found here: http://ekklesia360.screenstepslive.com/s/11328/m/78058/l/890306-icons

The rest of the content can be controlled via the section content area.