How to Install Linux on Chromebook [Step-by-Step Guide]

How to Install Linux on Chromebook [Step-by-Step Guide] : For some reason when i Do the sudo sh ~/Downloads/crouton -t xfce command, i recive a message like this: sh: 0: Refusing to exec /home/chronos/user/Downloads/crouton from noexec mount; see Chromium OS Docs - Shell scripts & noexec mounts
chronos@localhost / $ . why is this message appearing?

Did you do that?