User specific data

pls i need you to explain to me in very basic details how to use this component to show specific user details. i didn't understand the explanation on your site. I have a database table with four columns that contains username, password, id, details. Now i want the user when he logs into his joomla account as a registered joomla member to be able to view only his own record. And i want him to be identified by his joomla username, ie if he logs in he can only view his data and not the other records in the table.

Pls how can i achieve this, urgently respond.