You should just be able to perform these functions as you do in any application by doing one of the following:

• Select some content, right-click your selection and select 'Copy' or 'Cut' from the menu. To paste, right-click in a text area or input field and select 'Paste'.
• Select some content and press Ctrl+C to copy or Ctrl+X to cut. To paste, click in an input field or text area and press Ctrl+V.

In webpages you cannot cut content that is not in a text area or input field, and you cannot paste to somewhere other than a text area or input field. Some sites also use preventative measures to stop (or at least hinder - there is usually some way around it) copying (often to prevent plagiarism).

The Control "C" and Control "V" will work most of the time.

Use keyboard shortcuts if the buttons on the web page or other methods aren't working.

• Copy: Ctrl+C or Ctrl+Insert (Mac: Command + C)
• Paste: Ctrl+V or Shift+Insert (Mac: Command + V)
• Cut: Ctrl+X or Shift+Delete (Mac: Command + X)

• about:config page: dom.event.clipboardevents.enabled = false
• https://addons.mozilla.org/firefox/addon/nocopypaste/

• https://addons.mozilla.org/en-US/firefox/addon/righttoclick/

My exceptions to the original: This is in Windows 7 & in http://www.codecademy.com/courses/javascript-beginner-en-x9DnD/0/2?curriculum_id=506324b3a7dffd00020bf661# I also have the latest Copy Plain text extension.