To add a block click on where it goes on the page. An input field will show up saying “Start writing or type / to choose a block”.
Click the “choose a block” + and block options will open up. One of the options is a “Search for a block” field.
You don’t actually need the “/” to search. Just think of the thing you’re looking for and any way you might ask for it.
I am looking for a line that’s going to act like a separator on the page. In HTML that’s coded as <hr /> so I search for “hr” and get the “Separator” block. It also shows up if I search for “line” or “sepa”.