Casual Suite versions 3.0 or greater offer a simplified installation with the command casual-suite-init. By default this command will setup interfaces for all supported Casual modules, both built-in modes/modules and third party. Run this via execute-execute-command (M-x) or add the following Elisp to your Emacs initialization file.
(require 'casual-suite) (casual-suite-init)
Note that casual-suite-init will only work if Casual Suite is installed via package-install.
If à la carte style setup of Casual modules is desired, then confer with the install instructions provided by the following packages.