Bricks Builder is a site builder that allows great flexibility. You still need to know HTML and CSS to use it in my opinion, but, you can also get started with Bricks, without knowing those technologies. Using Bricks Builder will encourage us to learn more HTML, CSS and to some extent JavaScript, which is a good thing.
Bricks Builder is supplied as a WordPress theme and child theme.
You will install both the Bricks Theme and the Bricks Child Theme - they are provided as two separate zip files. Once installed, they will both appear in your Themes dashboard.
The next step is to activate Bricks so that it takes over from the previous theme running on your site. You can only do this with one of the Bricks themes; the one to activate is the Bricks Child theme.
By activating the child theme you are future-proofing any theme changes you might make. It means the Bricks main theme can be updated without overwriting any changes you happen to make to the child theme.
Of course, at this point you should put in your Bricks license key.
Some people like to keep one of the free themes lying around in case something ever goes wrong with the theme your using and you need to quickly switch to a simpler theme for testing.
In all the years I've used WordPress I've never had to to do, so in the interests of limiting clutter, I normally delete all the other themes apart from the one(s) I am literally using. However, if you want to leave another theme in the dashboard for this purpose go ahead.
This is what my themes page looks like once Bricks is installed and the child theme activated.