emacsのmultiple cursorsをインストールするとこまではできたのですが、その後の設定がよくわからずに困っています。requireとかはどのファイルに書けばいいのでしょうか？

そのあたりを詳しく書いているサイトがみあたりません。そんなことも知らないのかと思われるかもしれませんがよろしくお願いします。

以下は~/.emacsに記述しています

;; key bind (load-theme 'manoj-dark t) (define-key global-map [(S c)]
'kill-ring-save)

;; packcage init (require 'package) (add-to-list 'package-archives
'("melpa" . "https://melpa.org/packages/") t) (package-initialize)

(custom-set-variables ;; custom-set-variables was added by Custom.
;; If you edit it by hand, you could mess it up, so be careful. ;;
Your init file should contain only one such instance. ;; If there is
more than one, they won't work right. '(package-selected-packages
(quote (multiple-cursors)))) (custom-set-faces ;; custom-set-faces
was added by Custom. ;; If you edit it by hand, you could mess it up,
so be careful. ;; Your init file should contain only one such
instance. ;; If there is more than one, they won't work right. )

(require 'multiple-cursors)
(global-set-key (kbd "C-S-c C-S-c")'mc/edit-lines)
(global-set-key (kbd "C->") 'mc/mark-next-like-this)
(global-set-key (kbd "C-<") 'mc/mark-previous-like-this)
(global-set-key (kbd "C-c C-<") 'mc/mark-all-like-this)

requireできているのかわかりません。
とりあえず ctrl + Shift + c → ctrl + Shift + cを押してもなにも反応しません