Drop down box that will let users type if not on the list

Hello,

I'm a new user of asp.net with limited programming experience.  I developed a tool that lets the user edit the data on an SQl database.  I wanted to modify my dropdowns in such a way that if a user don't see the data he/she would like to input will allow the user to type in new data.  I've search the web and the threads I've read pointed me to use Combo box but its on Ajax control toolkit.  Is there an easier way to do this?

Thanks,

newASP_user