Add dropshadow in Layerslider

Hi Team,

I saw a previous question on this, however it’s still not clear to me.

You wrote: Please edit the text layer then go to Attributes, give it a unique selector id. For example “awesome-textshadow”. Go to Quick CSS field or edit custom.css, add the text shadow style on the unique selector:

#awesome-textshadow {
text-shadow: 5px 5px 3px #b5b5b5;
}

My question: how can I give it a unique selector id ? Give WHAT such an id ? And WHERE?

Thanks!

Best regards,
Ronald