Edit the page to which you want to add a block. The toolbar at the top left of the page contains six buttons. The leftmost button, Add Block (blue square with a plus sign inside), is for adding the different types of blocks to a page.
After clicking on Add Block, a list of blocks pops up. You can search for block types using the search bar or click through various categories to find a block type.
A full list of blocks can be found at this WordPress Support Page.