How to extract a cookie value

[nsYZY]

Hi,
I'm a complete layman so bear with me please.
Looking for someone to offer some assistance, I need to extract the document.cookie string from a website but literally have no idea how to find it - can anyone (patient) please help me?
thank you

 

[Rich]

https://addons.mozilla.org/en-GB/firefox/addon/cookies-manager-plus/