The Schema HowTo Block extension adds a new How-To Block to the Gutenberg Blocks list under Schema section, which allow entering instructions that explain how to achieve a result by performing a sequence of steps .
This extension requires Schema Premium version 1.0.8 and up to work properly.
1- Adding How-To Block
The HowTo Block extension once enabled, will add a new Block to the Gutenberg Blocks list under Schema section.

You can use this block to add How-To instructions where ever you want them to show on the page, and the extension will automatically append the schema.org markup.
1- Add How-To instructions
When you add a new How-To block to the editor, you will see a repeated field that will give you the option to add as many steps rows as you like.
2- Preview How-To
You can switch the block to preview mode, in this mode the fields will show on the right sidebar and you will be able to preview your How-To block while editing it.

Front-End HowTo
Here is how the final HowTo Block output looks like on the front-end:

Related:
Also, read about how to add HowTo schema markup for additional details.