docker run --publish [port]:5432 -e POSTGRES_PASSWORD [password] postgres:11N.B. Replace [port] with the port you want to expose (5432 is fine). Replace [password] with your desired password.
In the appsettings.json, set the Marten connection string to:
Host=localhost;Port=[port];User Id=postgres;Password=[password]
Again, replace [port] and [password] as above.
Run the application.