If you are using SQL Express, the easiest way to look at the table names is to download the SQL Server Management Studio Express. Then you can visually see every table, view, and stored procedure.

a VERY simple report to get all the users on your site would be:

select * from Users

Because regular SQL expressions are understood, the table name goes in the SQL statement (shown in red). You can use joins as well, but I usually prefer to design complex statements using Views (there is a graphical View builder in SQL Management Studio).

Robert