Adding ::before to a DIV

I can't seem to figure out how to get the ::before added to my DIV. I tried a custom code, but all it did was show the ::before. Where/how do I add this without having to edit the raw html?

   <div class="container">

Use this site for things like this

You'll get to learn basic things like this.

.container:before {
    content: "I just learned this!"

Most people use the single colon as a long time habit for needing to support IE8.


I do not seems to find a way to set "before" inside a div under bootstrap studio any help will be appreciated .

@chylby, you don't add it by way of HTML, you add it by way of CSS like my example I posted.


thanks @saj