HELP: case sensitive searching combobox and extracting info using php

[mortal2php]

hi

I have loaded two columns of data from mysql database to a combobox. Here's the problem:

How to I extract the selected item's text in the combobox which is
currently check?

Secondly how do I improve it by using case sensitive search from the combobox-type in textbox and highlights in combobox.

Please help me out. Provide some code if possible.

thanks