You cannot prevent people from copying text from your page. If you are trying to satisfy a “requirement” this may work for you:
<body oncopy="return false" oncut="return false" onpaste="return false">
How to disable Ctrl C/V using javascript for both internet explorer and firefox browsers
A more advanced aproach:
How to detect Ctrl+V, Ctrl+C using JavaScript?
Edit: I just want to emphasise that disabling copy/paste is annoying, won’t prevent copying and is 99% likely a bad idea.