Go to supabase.com and click Sign in

Enter your email and password, or create an account

Click New project and give it a name

Click Create new project

From the menu, open SQL Editor

Paste a SQL script with demo data (for example, a blog schema with posts and authors).
Example: supabase_blog_demo.sql

Click Run CTRL to execute the script

Click API Docs

Click API settings

Copy the Project URL and the anon key
You will need them in Silex
GraphQL endpoint format:
https://<project-ref>.supabase.co/graphql/v1

Open v3.silex.me

Click GitLab.com and authorize Silex to access your projects

From the dashboard, click Create website, enter a name, and click Create

Click your site to open the editor

Click to open Settings

Click CMS

Click Add data source

Enter a name and the Supabase Project URL with /graphql/v1 appended
Example:
https://<project-ref>.supabase.co/graphql/v1

Click to configure headers and add:
apikey: your Supabase anon keyAuthorization: <anon key> or a user access token if testing with auth
Click Test connection. It should display connected

Click Apply to save

You can now use Supabase data in Silex CMS to build your website
See also: Silex CMS docs