How to use toc

[YangYang48]

Hello，I have a question for you about generating toc.
I tried to write toc content in layouts/_default/single.html, it seems to have an effect, will be displayed on the left side of the article, but after sliding the page, toc will stay on the page and then disappear, please ask the author how to operate, because there is no basis for the web page, so I am not very clear