Since no one else has replied (we all figure you should be able to search for this on Google), here is something simple. Go to the following link for Hiren’s Boot CD.
https://www.hirensbootcd.orgGo to the Download section, scroll down to where the filename is and download the iso.
Then go to the USB Booting section and download the ISO2USB meant for creating a USB from the iso. Follow the instructions on that page for how to create the bootable USB.
Boot the created USB to a nice Windows PE environment that has many free tools. Be very patient as it takes a few minutes to boot up. Then use one of the hard disk imaging tools that are installed on it to clone your laptop drive to the external drive. Forget about using hdd raw copy.
I am assuming that the laptop drive is in good condition since you are currently booting from it. If not and it is failing and has bad sectors, and those tools fail to clone it, then look into hddsuperclone (see my signature). A live CD is available. You would then need to look for a tool to make a bootable USB from it, I prefer YUMI myself.