How to make a comment box in HTML, css, javascript, or jquery

Nevermind still disappears when reloaded

can i copy this and use it

I found this on google and i am learning to make site but i got idea to attach comment box in my working website.But i didn’t understand how to paste code on buttom of my site to check that code.Anyone can help me.I only know html css.

I want to know how to make a comment box and how to post it.
example : when you type a reply and it adds it to the website.