This is very basic. I would recommend learning the basics before trying to build any real program.
You need to create a trigger for your ‘retrieve’ button (which trigger ? I’m sure you can find that out).
In the previously mentioned trigger you have to write a <a href=”http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14261/selectinto_statement.htm”>SELECT INTO statement</a>.
Another way to do it would be creating a database block bound to your table, and calling the ‘execute_query’ built-in procedure from you button’s trigger.