advice, examples, creating front-end for postgresql

The most rudimentary Rails app consists of nothing much other than
CRUD operations on tables in a database. Nothing special about what
kind of database, you just have to say what kind it is in the
config/database.yml file.

Basic scaffolding generates models that fit the exact scenario you're
describing: create, read, update, delete (CRUD) records in various
tables in your data base.

If you're database tables have relationships that you care about, you
need to dig a little deeper of course, and look at ActiveRecord

Assuming your postgresql database already exists, you can still run
the scaffolding generators for it, but it becomes a bit more
complicated from then on. You don't want to run the migrations they
generate, as they will destroy the existing database. Likewise, using
rake to run tests will fail as it checks to see that all migrations
have been applied.