Basic combo box question

[sea]

I'm trying to work with combo box, which will display graphically data I store in access DB. Each index no. has a column in the DB. means: choose option with index 1 from drop down list; get data & graph for column 1. Very simple & strait forward. I just cannot seem to grasp the idea of this combo box & what's running it. What is the event which will trigger the change of display? How do I pass item index no. to the method that connected to DB? You may send me a link to a site where I can view some simple examples of those? I've been looking all over & couldn't find something useful. sea#